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Author	Do, M.T.; Gauquelin, N.; Nguyen, M.D.; Wang, J.; Verbeeck, J.; Blom, F.; Koster, G.; Houwman, E.P.; Rijnders, G.
Title	Interfacial dielectric layer as an origin of polarization fatigue in ferroelectric capacitors			Type	A1 Journal article
Year	2020	Publication	Scientific Reports	Abbreviated Journal	Sci Rep-Uk
Volume	10	Issue	1	Pages	7310
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Origins of polarization fatigue in ferroelectric capacitors under electric field cycling still remain unclear. Here, we experimentally identify origins of polarization fatigue in ferroelectric PbZr0.52Ti0.48O3 (PZT) thin-film capacitors by investigating their fatigue behaviours and interface structures. The PZT layers are epitaxially grown on SrRuO3-buffered SrTiO3 substrates by a pulsed laser deposition (PLD), and the capacitor top-electrodes are various, including SrRuO3 (SRO) made by in-situ PLD, Pt by in-situ PLD (Pt-inPLD) and ex-situ sputtering (Pt-sputtered). We found that fatigue behaviour of the capacitor is directly related to the top-electrode/PZT interface structure. The Pt-sputtered/PZT/SRO capacitor has a thin defective layer at the top interface and shows early fatigue while the Pt-inPLD/PZT/SRO and SRO/PZT/SRO capacitor have clean top-interfaces and show much more fatigue resistance. The defective dielectric layer at the Pt-sputtered/PZT interface mainly contains carbon contaminants, which form during the capacitor ex-situ fabrication. Removal of this dielectric layer significantly delays the fatigue onset. Our results clearly indicate that dielectric layer at ferroelectric capacitor interfaces is the main origin of polarization fatigue, as previously proposed in the charge injection model.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000559953800003	Publication Date	2020-04-30
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2045-2322	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.6	Times cited	18	Open Access	OpenAccess
Notes	; The authors acknowledge the financial support of the Nederlandse Organisatie voor Wetenschappelijk Onderzoek through Grant No. F62.3.15559. ;			Approved	Most recent IF: 4.6; 2020 IF: 4.259
Call Number	EMAT @ emat @c:irua:169865			Serial	6374
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Author	Lebedev, N.; Stehno, M.; Rana, A.; Reith, P.; Gauquelin, N.; Verbeeck, J.; Hilgenkamp, H.; Brinkman, A.; Aarts, J.
Title	Gate-tuned anomalous Hall effect driven by Rashba splitting in intermixed LaAlO3/GdTiO3/SrTiO3			Type	A1 Journal article
Year	2021	Publication	Scientific Reports	Abbreviated Journal	Sci Rep-Uk
Volume	11	Issue	1	Pages	10726
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	The Anomalous Hall Effect (AHE) is an important quantity in determining the properties and understanding the behaviour of the two-dimensional electron system forming at the interface of SrTiO<sub>3</sub>-based oxide heterostructures. The occurrence of AHE is often interpreted as a signature of ferromagnetism, but it is becoming more and more clear that also paramagnets may contribute to AHE. We studied the influence of magnetic ions by measuring intermixed LaAlO<sub>3</sub>/GdTiO<sub>3</sub>/SrTiO<sub>3</sub>at temperatures below 10 K. We find that, as function of gate voltage, the system undergoes a Lifshitz transition while at the same time an onset of AHE is observed. However, we do not observe clear signs of ferromagnetism. We argue the AHE to be due to the change in Rashba spin-orbit coupling at the Lifshitz transition and conclude that also paramagnetic moments which are easily polarizable at low temperatures and high magnetic fields lead to the presence of AHE, which needs to be taken into account when extracting carrier densities and mobilities.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000658820100014	Publication Date	2021-05-21
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2045-2322	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.259	Times cited	5	Open Access	OpenAccess
Notes	J.V. and N.G. acknowledge funding from the Geconcentreerde Onderzoekacties (GOA) project “Solarpaint” of the University of Antwerp and the European Union’s horizon 2020 research and innovation programme ESTEEM3 under grant agreement 823717. The Qu-Ant-EM microscope used in this study was partly funded by the Hercules fund from the Flemish Government.; esteem3TA; esteem3reported			Approved	Most recent IF: 4.259
Call Number	EMAT @ emat @c:irua:179608			Serial	6822
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Author	Jovanović, Z.; Gauquelin, N.; Koster, G.; Rubio-Zuazo, J.; Ghosez, P.; Verbeeck, J.; Suvorov, D.; Spreitzer, M.
Title	Simultaneous heteroepitaxial growth of SrO (001) and SrO (111) during strontium-assisted deoxidation of the Si (001) surface			Type	A1 Journal article
Year	2020	Publication	Rsc Advances	Abbreviated Journal	Rsc Adv
Volume	10	Issue	52	Pages	31261-31270
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Epitaxial integration of transition-metal oxides with silicon brings a variety of functional properties to the well-established platform of electronic components. In this process, deoxidation and passivation of the silicon surface are one of the most important steps, which in our study were controlled by an ultra-thin layer of SrO and monitored by using transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), synchrotron X-ray diffraction (XRD) and reflection high energy electron diffraction (RHEED) methods. Results revealed that an insufficient amount of SrO leads to uneven deoxidation of the silicon surface<italic>i.e.</italic>formation of pits and islands, whereas the composition of the as-formed heterostructure gradually changes from strontium silicide at the interface with silicon, to strontium silicate and SrO in the topmost layer. Epitaxial ordering of SrO, occurring simultaneously with silicon deoxidation, was observed. RHEED analysis has identified that SrO is epitaxially aligned with the (001) Si substrate both with SrO (001) and SrO (111) out-of-plane directions. This observation was discussed from the point of view of SrO desorption, SrO-induced deoxidation of the Si (001) surface and other interfacial reactions as well as structural ordering of deposited SrO. Results of the study present an important milestone in understanding subsequent epitaxial integration of functional oxides with silicon using SrO.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000566579400025	Publication Date	2020-08-24
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2046-2069	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.9	Times cited	1	Open Access	OpenAccess
Notes	Vlaamse regering, Hercules Fund ; Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja, III 45006 ; Javna Agencija za Raziskovalno Dejavnost RS, J2-9237 P2-0091 ; Fonds Wetenschappelijk Onderzoek, G.0044.13N ; Ministerio de Ciencia, Innovación y Universidades; Universiteit Antwerpen, GOA project Solarpaint ; F.R.S.-FNRS, PDR project PROMOSPAN ; Consejo Superior de Investigaciones Cientificas; University of Liège, ARC project AIMED ; Ministry of Education, Science and Sport, M.ERA-NET project SIOX ;			Approved	Most recent IF: 3.9; 2020 IF: 3.108
Call Number	EMAT @ emat @c:irua:172059			Serial	6416
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Author	Benedoue, S.; Benedet, M.; Gasparotto, A.; Gauquelin, N.; Orekhov, A.; Verbeeck, J.; Seraglia, R.; Pagot, G.; Rizzi, G.A.; Balzano, V.; Gavioli, L.; Noto, V.D.; Barreca, D.; Maccato, C.
Title	Insights into the Photoelectrocatalytic Behavior of gCN-Based Anode Materials Supported on Ni Foams			Type	A1 Journal article
Year	2023	Publication	Nanomaterials	Abbreviated Journal	Nanomaterials-Basel
Volume	13	Issue	6	Pages	1035
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Graphitic carbon nitride (gCN) is a promising n-type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g., by depositing gCN onto conductive and porous scaffolds, tailoring its nanoscale morphology, and functionalizing it with suitable cocatalysts. The present study reports on a simple and easily controllable synthesis of gCN flakes on Ni foam substrates by electrophoretic deposition (EPD), and on their eventual decoration with Co-based cocatalysts [CoO, CoFe2O4, cobalt phosphate (CoPi)] via radio frequency (RF)-sputtering or electrodeposition. After examining the influence of processing conditions on the material characteristics, the developed systems are comparatively investigated as (photo)anodes for water splitting and photoelectrocatalysts for the degradation of a recalcitrant water pollutant [potassium hydrogen phthalate (KHP)]. The obtained results highlight that while gCN decoration with Co-based cocatalysts boosts water splitting performances, bare gCN as such is more efficient in KHP abatement, due to the occurrence of a different reaction mechanism. The related insights, provided by a multi-technique characterization, may provide valuable guidelines for the implementation of active nanomaterials in environmental remediation and sustainable solar-to-chemical energy conversion.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000960297000001	Publication Date	2023-03-13
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2079-4991	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	5.3	Times cited	3	Open Access	OpenAccess
Notes	The present work was financially supported by CNR (Progetti di Ricerca @CNR—avviso 2020—ASSIST), Padova University (P-DiSC#04BIRD2020-UNIPD EUREKA, DOR 2020–2022), AMGA Foundation (NYMPHEA project), INSTM Consortium (INSTM21PDGASPAROTTO—NANOMAT, INSTM21PDBARMAC—ATENA) and the European Union’s Horizon 2020 research and innovation program under grant agreement No. 823717—ESTEEM3. The FWO-Hercules fund G0H4316N ‘Direct electron detector for soft matter TEM’ is also acknowledged. Many thanks are also due to Dr. Riccardo Lorenzin for his support to experimental activities.; esteem3reported; esteem3TA			Approved	Most recent IF: 5.3; 2023 IF: 3.553
Call Number	EMAT @ emat @c:irua:196115			Serial	7378
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Author	Gauquelin, N.; Zhang, H.; Zhu, G.; Wei, J.Y.T.; Botton, G.A.
Title	Atomic-scale identification of novel planar defect phases in heteroepitaxial YBa₂Cu₃O_7-\delta thin films			Type	A1 Journal article
Year	2018	Publication	AIP advances	Abbreviated Journal	Aip Adv
Volume	8	Issue	5	Pages	055022
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	We have discovered two novel types of planar defects that appear in heteroepitaxial YBa2Cu3O7-delta(YBCO123) thin films, grown by pulsed-laser deposition (PLD) either with or without a La2/3Ca1/3MnO3 (LCMO) overlayer, using the combination of highangle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging and electron energy loss spectroscopy (EELS) mapping for unambiguous identification. These planar lattice defects are based on the intergrowth of either a BaO plane between two CuO chains or multiple Y-O layers between two CuO2 planes, resulting in non-stoichiometric layer sequences that could directly impact the high-Tc superconductivity. (C) 2018 Author(s).
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Corporate Author				Thesis
Publisher	American Institute of Physics	Place of Publication	Melville, NY	Editor
Language		Wos	000433954000022	Publication Date	2018-05-21
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2158-3226	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	1.568	Times cited	1	Open Access	OpenAccess
Notes	; We are thankful to Julia Huang for FIB TEM sample preparation. This work is supported by NSERC (through Discovery Grants to GAB and JYTW) and CIFAR. The electron microscopy work was carried out at the Canadian Centre for Electron Microscopy, a National Facility supported by McMaster University, the Canada Foundation for Innovation and NSERC. N.G. acknowledges H. Idrissi for useful discussions. ;			Approved	Most recent IF: 1.568
Call Number	UA @ lucian @ c:irua:152063			Serial	5013
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Author	Do, M.T.; Gauquelin, N.; Nguyen, M.D.; Blom, F.; Verbeeck, J.; Koster, G.; Houwman, E.P.; Rijnders, G.
Title	Interface degradation and field screening mechanism behind bipolar-cycling fatigue in ferroelectric capacitors			Type	A1 Journal article
Year	2021	Publication	Apl Materials	Abbreviated Journal	Apl Mater
Volume	9	Issue	2	Pages	021113
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Polarization fatigue, i.e., the loss of polarization of ferroelectric capacitors upon field cycling, has been widely discussed as an interface related effect. However, mechanism(s) behind the development of fatigue have not been fully identified. Here, we study the fatigue mechanisms in Pt/PbZr0.52Ti0.48O3/SrRuO3 (Pt/PZT/SRO) capacitors in which all layers are fabricated by pulsed laser deposition without breaking the vacuum. With scanning transmission electron microscopy, we observed that in the fatigued capacitor, the Pt/PZT interface becomes structurally degraded, forming a 5 nm-10 nm thick non-ferroelectric layer of crystalline ZrO2 and diffused Pt grains. We then found that the fatigued capacitors can regain the full initial polarization switching if the externally applied field is increased to at least 10 times the switching field of the pristine capacitor. These findings suggest that polarization fatigue is driven by a two-step mechanism. First, the transient depolarization field that repeatedly appears during the domain switching under field cycling causes decomposition of the metal/ferroelectric interface, resulting in a non-ferroelectric degraded layer. Second, this interfacial non-ferroelectric layer screens the external applied field causing an increase in the coercive field beyond the usually applied maximum field and consequently suppresses the polarization switching in the cycled capacitor. Our work clearly confirms the key role of the electrode/ferroelectric interface in the endurance of ferroelectric-based devices.
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Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000630052100006	Publication Date	2021-02-09
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2166-532x	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.335	Times cited	5	Open Access	OpenAccess
Notes	This work was supported by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek through Grant No. F62.3.15559. The Qu-Ant-EM microscope and the direct electron detector were partly funded by the Hercules fund from the Flemish Government. N.G. and J.V. acknowledge funding from the GOA project “Solarpaint” of the University of Antwerp. This work has also received funding from the European Union's Horizon 2020 research and innovation program under Grant No. 823717-ESTEEM3. We acknowledge D. Chezganov for his useful insights.			Approved	Most recent IF: 4.335
Call Number	UA @ admin @ c:irua:177663			Serial	6783
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Author	Verdierre, G.; Gauquelin, N.; Jannis, D.; Birkhölzer, Y.A.; Mallik, S.; Verbeeck, J.; Bibes, M.; Koster, G.
Title	Epitaxial growth of the candidate ferroelectric Rashba material SrBiO₃by pulsed laser deposition			Type	A1 Journal article
Year	2023	Publication	APL materials	Abbreviated Journal
Volume	11	Issue	3	Pages	031109
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Among oxides, bismuthates have been gaining much interest due to their unique features. In addition to their superconducting properties, they show potential for applications as topological insulators and as possible spin-to-charge converters. After being first investigated in their bulk form in the 1980s, bismuthates have been successfully grown as thin films. However, most efforts have focused on BaBiO<sub>3</sub>, with SrBiO<sub>3</sub>receiving only little attention. Here, we report the growth of epitaxial films of SrBiO<sub>3</sub>on both TiO<sub>2</sub>-terminated SrTiO<sub>3</sub>and NdO-terminated NdScO<sub>3</sub>substrates by pulsed laser deposition. SrBiO<sub>3</sub>has a pseudocubic lattice constant of ∼4.25 Å and grows relaxed on NdScO<sub>3</sub>. Counter-intuitively, it grows with a slight tensile strain on SrTiO<sub>3</sub>despite a large lattice mismatch, which should induce compressive strain. High-resolution transmission electron microscopy reveals that this occurs as a consequence of structural domain matching, with blocks of 10 SrBiO<sub>3</sub>unit planes matching blocks of 11 SrTiO<sub>3</sub>unit planes. This work provides a framework for the synthesis of high quality perovskite bismuthates films and for the understanding of their interface interactions with homostructural substrates.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000953363800004	Publication Date	2023-03-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2166-532X	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	6.1	Times cited		Open Access	OpenAccess
Notes	This work received support from the ERC Advanced grant (Grant No. 833973) “FRESCO” and funding from the European Union’s Horizon 2020 Research and Innovation Program under Grant Agreement No. 823717—ESTEEM3, Van Gogh travel grant, Nuffic, The Netherlands (CF No. 42582SB).; esteem3reported; esteem3TA			Approved	Most recent IF: 6.1; 2023 IF: 4.335
Call Number	EMAT @ emat @c:irua:196135			Serial	7377
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Author	Ignatova, K.; Vlasov, E.; Seddon, S.D.; Gauquelin, N.; Verbeeck, J.; Wermeille, D.; Bals, S.; Hase, T.P.A.; Arnalds, U.B.
Title	Phase coexistence induced surface roughness in V2O3/Ni magnetic heterostructures			Type	A1 Journal Article
Year	2024	Publication	APL Materials	Abbreviated Journal
Volume	12	Issue	4	Pages
Keywords	A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract	We present an investigation of the microstructure changes in V2O3 as it goes through its inherent structural phase transition. Using V2O3 films with a well-defined crystal structure deposited by reactive magnetron sputtering on r-plane Al2O3 substrates, we study the phase coexistence region and its impact on the surface roughness of the films and the magnetic properties of overlying Ni magnetic layers in V2O3/Ni hybrid magnetic heterostructures. The simultaneous presence of two phases in V2O3 during its structural phase transition was identified with high resolution x-ray diffraction and led to an increase in surface roughness observed using x-ray reflectivity. The roughness reaches its maximum at the midpoint of the transition. In V2O3/Ni hybrid heterostructures, we find a concomitant increase in the coercivity of the magnetic layer correlated with the increased roughness of the V2O3 surface. The chemical homogeneity of the V2O3 is confirmed through transmission electron microscopy analysis. High-angle annular dark field imaging and electron energy loss spectroscopy reveal an atomically flat interface between Al2O3 and V2O3, as well as a sharp interface between V2O3 and Ni.
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Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	001202661800003	Publication Date	2024-04-01
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2166-532X	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	6.1	Times cited		Open Access
Notes	This work was supported by the funding from the University of Iceland Research Fund, the Icelandic Research Fund Grant No. 207111. Instrumentation funding from the Icelandic Infrastructure Fund is acknowledged. This work was based on experiments per- formed at the BM28 (XMaS) beamline at the European Synchrotron Radiation Facility, Grenoble, France. XMaS is a National Research Facility funded by the UK EPSRC and managed by the Universi- ties of Liverpool and Warwick. This project has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 823717—ESTEEM3.			Approved	Most recent IF: 6.1; 2024 IF: 4.335
Call Number	EMAT @ emat @c:irua:205569			Serial	9120
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Author	Monico, L.; Rosi, F.; Vivani, R.; Cartechini, L.; Janssens, K.; Gauquelin, N.; Chezganov, D.; Verbeeck, J.; Cotte, M.; D'Acapito, F.; Barni, L.; Grazia, C.; Buemi, L.P.; Andral, J.-L.; Miliani, C.; Romani, A.
Title	Deeper insights into the photoluminescence properties and (photo)chemical reactivity of cadmium red (CdS_1-xSe_x) paints in renowned twentieth century paintings by state-of-the-art investigations at multiple length scales			Type	A1 Journal article
Year	2022	Publication	The European Physical Journal Plus	Abbreviated Journal	Eur Phys J Plus
Volume	137	Issue	3	Pages	311
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Antwerp X-ray Imaging and Spectroscopy (AXIS)
Abstract	Cadmium red is the name used for denoting a class of twentieth century artists' pigments described by the general formula CdS1-xSex. For their vibrant hues and excellent covering power, a number of renowned modern and contemporary painters, including Jackson Pollock, often used cadmium reds. As direct band gap semiconductors, CdS1-xSex compounds undergo direct radiative recombination (with emissions from the green to orange region) and radiative deactivation from intragap trapping states due to crystal defects, which give rise to two peculiar red-NIR emissions, known as deep level emissions (DLEs). The positions of the DLEs mainly depend on the Se content of CdS1-xSex; thus, photoluminescence and diffuse reflectance vis-NIR spectroscopy have been profitably used for the non-invasive identification of different cadmium red varieties in artworks over the last decade. Systematic knowledge is however currently lacking on what are the parameters related to intrinsic crystal defects of CdS1-xSex and environmental factors influencing the spectral properties of DLEs as well as on the overall (photo)chemical reactivity of cadmium reds in paint matrixes. Here, we present the application of a novel multi-length scale and multi-method approach to deepen insights into the photoluminescence properties and (photo)chemical reactivity of cadmium reds in oil paintings by combining both well established and new non-invasive/non-destructive analytical techniques, including macro-scale vis-NIR and vibrational spectroscopies and micro-/nano-scale advanced electron microscopy mapping and X-ray methods employing synchrotron radiation and conventional sources. Macro-scale vis-NIR spectroscopy data obtained from the in situ non-invasive analysis of nine masterpieces by Gerardo Dottori, Jackson Pollock and Nicolas de Stael allowed classifying the CdS1-xSex-paints in three groups, according to the relative intensity of the two DLE bands. These outcomes, combined with results from micro-/nano-scale electron microscopy mapping and X-ray analysis of a set of CdS1-xSex powders and artificially aged paint mock-ups, indicated that the relative intensity of DLEs is not affected by the morphology, microstructure and local atomic environment of the pigment particles but it is influenced by the presence of moisture. Furthermore, the extensive study of artificially aged oil paint mock-ups permitted us to provide first evidence of the tendency of cadmium reds toward photo-degradation and to establish that the conversion of CdS1-xSex to CdSO4 and/or oxalates is triggered by the oil binding medium and moisture level and depends on the Se content. Based on these findings, we could interpret the localized presence of CdSO4 and cadmium oxalate as alteration products of the original cadmium red paints in two paintings by Pollock.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000765807600002	Publication Date	0000-00-00
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2190-5444	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.4	Times cited	3	Open Access	OpenAccess
Notes	g The research was financially supported by the EU FP7 and Horizon 2020 Projects CHARISMA (FP7-INFRASTRUCTURES, GA No. 228330), IPERION-CH (H2020-INFRAIA-2014-2015, GA No. 654028), IPERION-HS (H2020-INFRAIA-2019-1, GA No. 871034) and ESTEEM3 (Research and innovation programme, GA No. 823717) and the Italian project AMIS (Dipartimenti di Eccellenza 2018–2022, funded by MIUR and Perugia University). For the beamtime grants received, we thank ESRF-ID21 (Experiment No. HG156 and in-house beamtimes) and the CERIC-ERIC Research Infrastructure for the investigations at ESRF-BM08 (LISA) beamline (Proposal Id: 20207042). D.C. acknowledges TOP/BOF funding of the University of Antwerp.; esteem3reported; esteem3TA			Approved	Most recent IF: 3.4
Call Number	UA @ admin @ c:irua:187375			Serial	7060
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Author	Herzog, M.J.; Gauquelin, N.; Esken, D.; Verbeeck, J.; Janek, J.
Title	Facile dry coating method of high-nickel cathode material by nanostructured fumed alumina (Al2O3) improving the performance of lithium-ion batteries			Type	A1 Journal article
Year	2021	Publication	Energy technology	Abbreviated Journal
Volume	9	Issue	4	Pages	2100028
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Surface coating is a crucial method to mitigate the aging problem of high-Ni cathode active materials (CAMs). By avoiding the direct contact of the CAM and the electrolyte, side reactions are hindered. Commonly used techniques like wet or ALD coating are time consuming and costly. Therefore, a more cost-effective coating technique is desirable. Herein, a facile and fast dry powder coating process for CAMs with nanostructured fumed metal oxides are reported. As the model case, the coating of high-Ni NMC (LiNi0.7Mn0.15Co0.15O2) by nanostructured fumed Al2O3 is investigated. A high coverage of the CAM surface with an almost continuous coating layer is achieved, still showing some porosity. Electrochemical evaluation shows a significant increase in capacity retention, cycle life and rate performance of the coated NMC material. The coating layer protects the surface of the CAM successfully and prevents side reactions, resulting in reduced solid electrolyte interface (SEI) formation and charge transfer impedance during cycling. A mechanism on how the coating layer enhances the cycling performance is hypothesized. The stable coating layer effectively prevents crack formation and particle disintegration of the NMC. In depth analysis indicates partial formation of LixAl2O3/LiAlO2 in the coating layer during cycling, enhancing lithium ion diffusivity and thus, also the rate performance.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000621000700001	Publication Date	2021-01-23
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2194-4296; 2194-4288	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	25	Open Access	OpenAccess
Notes	The authors would like to thank Erik Peldszus and Steve Rienecker for the support with scanning electron microscopy and X-ray photoelectron spectroscopy analysis. The Qu-Ant-EM microscope and the direct electron detector were partly funded by the Hercules fund from the Flemish Government. N.G. and J.V. acknowledge funding from GOA project “Solarpaint” of the University of Antwerp. Funding from the Flemish Research Fund (FWO) project G0F1320N is acknowledged.; Open access funding enabled and organized by Projekt DEAL.			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:176670			Serial	6724
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Author	Smolin, S.Y.; Choquette, A.K.; Wilks, R.G.; Gauquelin, N.; Félix, R.; Gerlach, D.; Ueda, S.; Krick, A.L.; Verbeeck, J.; Bär, M.; Baxter, J.B.; May, S.J.
Title	Energy Level Alignment and Cation Charge States at the LaFeO₃/LaMnO₃(001) Heterointerface			Type	A1 Journal article
Year	2017	Publication	Advanced Materials Interfaces	Abbreviated Journal	Adv Mater Interfaces
Volume	4	Issue	4	Pages	1700183
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The electronic properties of LaFeO 3 /LaMnO 3 epitaxial heterojunctions are investigated to determine the valence and conduction band offsets and the nominal Mn and Fe valence states at the interface. Studying a systematic series of (LaFeO 3 ) n /(LaMnO 3 ) m bilayers (m ≈ 50) epitaxially grown in the (001) orientation using molecular beam epitaxy, layer-resolved electron energy loss spectroscopy reveals a lack of significant interfacial charge transfer, with a nominal 3+ valence state observed for both Mn and Fe across the interface. Through a combination of variable angle spectroscopic ellipsometry and hard X-ray photoelectron spectroscopy, type I energy level alignments are obtained at the LaFeO 3 /LaMnO 3 interface with positive valence and conduction band offsets of (1.20 ± 0.07) eV and (0.5–0.7 ± 0.3) eV, respectively, with minimal band bending. Variable temperature resistivity measurements reveal that the bilayers remain insulating and that the presence of the heterojunction does not result in a conducting interface.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000406068400011	Publication Date	2017-04-26
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2196-7350	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.279	Times cited	14	Open Access	Not_Open_Access
Notes	The authors thank Dmytro Nykypanchuk for assistance with the near- infrared ellipsometry measurement of the LaMnO 3 film. S.Y.S., A.K.C., J.B.B, and S.J.M. acknowledge funding from the National Science Foundation under grant number ECCS-1201957. S.Y.S. acknowledges additional funding from the German Academic Exchange Service (DAAD) through the Research Internships in Science and Engineering (RISE) professional program 2015 ID 5708457. A.L.K. was funded by the National Science Foundation under grant number DMR-1151649. J.V. and N.G. acknowledge funding through the GOA project “Solarpaint” of the University of Antwerp and from the FWO project G.0044.13N (Charge ordering). The microscope used in this work was partly funded by the Hercules Fund from the Flemish Government. Ellipsometry measurements of the LaMnO 3 film were carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-ACO2-98CH10886. S.U. would like to thank the staff of HiSOR, Hiroshima University, and JAEA/Spring-8 for the development of HAXPES at BL15XU of SPring-8. The HAXPES measurements were performed with approval of NIMS Synchrotron X-ray Station (Proposal No. 2015B4601), and were partly supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. The authors also thank HZB for the allocation of synchrotron radiation beamtime for HAXPES/XANES measurements. R.G.W., R.F, and M.B. are grateful to the Impuls- und Vernetzungsfonds of the Helmholtz Association (VH-NG-423).; National Science Foundation, ECCS-1201957 DMR-1151649 ; Deutscher Akademischer Austauschdienst, 2015 ID 5708457 ; GOA project; Fonds Wetenschappelijk Onderzoek, G.0044.13N ; Flemish Government; U.S. Department of Energy, DE-ACO2-98CH10886 ; Vernetzungsfonds of the Helmholtz Association, VH-NG-423 ;			Approved	Most recent IF: 4.279
Call Number	EMAT @ emat @ c:irua:142346UA @ admin @ c:irua:142346			Serial	4553
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Author	Li, L.; Liao, Z.; Gauquelin, N.; Minh Duc Nguyen; Hueting, R.J.E.; Gravesteijn, D.J.; Lobato, I.; Houwman, E.P.; Lazar, S.; Verbeeck, J.; Koster, G.; Rijnders, G.
Title	Epitaxial stress-free growth of high crystallinity ferroelectric PbZr_0.52Ti_0.48O₃ on GaN/AlGaN/Si(111) substrate			Type	A1 Journal article
Year	2018	Publication	Advanced Materials Interfaces	Abbreviated Journal	Adv Mater Interfaces
Volume	5	Issue	2	Pages	1700921
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	<script type='text/javascript'>document.write(unpmarked('Due to its physical properties gallium-nitride (GaN) is gaining a lot of attention as an emerging semiconductor material in the field of high-power and high-frequency electronics applications. Therefore, the improvement in the performance and/or perhaps even extension in functionality of GaN based devices would be highly desirable. The integration of ferroelectric materials such as lead-zirconate-titanate (PbZrxTi1-xO3) with GaN has a strong potential to offer such an improvement. However, the large lattice mismatch between PZT and GaN makes the epitaxial growth of Pb(Zr1-xTix)O-3 on GaN a formidable challenge. This work discusses a novel strain relaxation mechanism observed when MgO is used as a buffer layer, with thicknesses down to a single unit cell, inducing epitaxial growth of high crystallinity Pb(Zr0.52Ti0.48)O-3 (PZT) thin films. The epitaxial PZT films exhibit good ferroelectric properties, showing great promise for future GaN device applications.'));
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000423173800005	Publication Date	2017-11-27
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2196-7350	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	4.279	Times cited	15	Open Access	Not_Open_Access
Notes	; L.L., Z.L.L., and N.G. contributed equally to this work. L.L. acknowledges financial support from Nano Next NL (Grant no. 7B 04). The authors acknowledge NXP for providing the GaN/AlGaN/Si (111) wafer. N.G. acknowledges funding from the Geconcentreerde Onderzoekacties (GOA) project “Solarpaint” of the University of Antwerp and J.V. acknowledges funding from the Research Foundation Flanders (FWO, Belgium) project 42/FA070100/6088 “nieuwe eigenschappen in complexe Oxides.” N.G. acknowledges the EUROTAPES project (FP7-NMP.2011.2.2-1 Grant no. 280432) which partly funded this study. ;			Approved	Most recent IF: 4.279
Call Number	UA @ lucian @ c:irua:148427UA @ admin @ c:irua:148427			Serial	4872
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Author	Chen, B.; Gauquelin, N.; Green, R.J.; Verbeeck, J.; Rijnders, G.; Koster, G.
Title	Asymmetric Interfacial Intermixing Associated Magnetic Coupling in LaMnO3/LaFeO3 Heterostructures			Type	A1 Journal article
Year	2021	Publication	Frontiers in physics	Abbreviated Journal	Front. Phys.
Volume	9	Issue		Pages
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The structural and magnetic properties of LaMnO<sub>3</sub>/LaFeO<sub>3</sub>(LMO/LFO) heterostructures are characterized using a combination of scanning transmission electron microscopy, electron energy-loss spectroscopy, bulk magnetometry, and resonant x-ray reflectivity. Unlike the relatively abrupt interface when LMO is deposited on top of LFO, the interface with reversed growth order shows significant cation intermixing of Mn<sup>3+</sup>and Fe<sup>3+</sup>, spreading ∼8 unit cells across the interface. The asymmetric interfacial chemical profiles result in distinct magnetic properties. The bilayer with abrupt interface shows a single magnetic hysteresis loop with strongly enhanced coercivity, as compared to the LMO plain film. However, the bilayer with intermixed interface shows a step-like hysteresis loop, associated with the separate switching of the “clean” and intermixed LMO sublayers. Our study illustrates the key role of interfacial chemical profile in determining the functional properties of oxide heterostructures.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000745284500001	Publication Date	2021-12-14
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2296-424X	ISBN		Additional Links	UA library record; WoS full record
Impact Factor		Times cited	1	Open Access	OpenAccess
Notes	This work is supported by the international M-ERA.NET project SIOX (project 4288) and H2020 project ULPEC (project 732642). The X-Ant-EM microscope and the direct electron detector were partly funded by the Hercules fund from the Flemish Government. NG and JV acknowledge funding from GOA project “Solarpaint” of the University of Antwerp. RG was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). Part of the research described in this paper was performed at the Canadian Light Source, a national research facility of the University of Saskatchewan, which is supported by the Canada Foundation for Innovation (CFI), NSERC, the National Research Council (NRC), the Canadian Institutes of Health Research (CIHR), the Government of Saskatchewan, and the University of Saskatchewan.			Approved	Most recent IF: NA
Call Number	EMAT @ emat @c:irua:185176			Serial	6901
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Author	Psilodimitrakopoulos, S.; Orekhov, A.; Mouchliadis, L.; Jannis, D.; Maragkakis, G.M.; Kourmoulakis, G.; Gauquelin, N.; Kioseoglou, G.; Verbeeck, J.; Stratakis, E.
Title	Optical versus electron diffraction imaging of Twist-angle in 2D transition metal dichalcogenide bilayers			Type	A1 Journal article
Year	2021	Publication	npj 2D Materials and Applications	Abbreviated Journal
Volume	5	Issue	1	Pages	77
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Atomically thin two-dimensional (2D) materials can be vertically stacked with van der Waals bonds, which enable interlayer coupling. In the particular case of transition metal dichalcogenide (TMD) bilayers, the relative direction between the two monolayers, coined as twist-angle, modifies the crystal symmetry and creates a superlattice with exciting properties. Here, we demonstrate an all-optical method for pixel-by-pixel mapping of the twist-angle with a resolution of 0.55(degrees), via polarization-resolved second harmonic generation (P-SHG) microscopy and we compare it with four-dimensional scanning transmission electron microscopy (4D STEM). It is found that the twist-angle imaging of WS2 bilayers, using the P-SHG technique is in excellent agreement with that obtained using electron diffraction. The main advantages of the optical approach are that the characterization is performed on the same substrate that the device is created on and that it is three orders of magnitude faster than the 4D STEM. We envisage that the optical P-SHG imaging could become the gold standard for the quality examination of TMD superlattice-based devices.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000694849200001	Publication Date	2021-09-09
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2397-7132	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	4	Open Access	OpenAccess
Notes	This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call European R & T Cooperation-Grant Act of Hellenic Institutions that have successfully participated in Joint Calls for Proposals of European Networks ERA NETS (National project code: GRAPH-EYE T8 Epsilon Rho Alpha 2-00009 and European code: 26632, FLAGERA). L.M., G.Ko. and G.Ki. acknowledge funding by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project No: HFRI-FM17-3034). GKi, S.P. and G.M.M. acknowledge funding from a research co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme “Human Resources Development, Education and Lifelong Learning 2014-2020” in the context of the project “Crystal quality control of two-dimensional materials and their heterostructures via imaging of their non-linear optical properties” (MIS 5050340)“. J.V acknowledges funding from FWO G093417N ('Compressed sensing enabling low dose imaging in transmission electron microscopy') from the Flanders Research Fund, EU. J.V. and N.G. acknowledge funding from the European Union under the Horizon 2020 programme within a contract for Integrating Activities for Advanced Communities No 823717-ESTEEM3. J.V. N.G. and A.O. acknowledge funding through a GOA project ”Solarpaint" of the University of Antwerp.			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:181610			Serial	6877
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Author	Behera, B.C.; Jana, S.; Bhat, S.G.; Gauquelin, N.; Tripathy, G.; Kumar, P.S.A.; Samal, D.
Title	Evidence for exchange bias coupling at the perovskite/brownmillerite interface in spontaneously stabilized SrCoO_3-\delta/SrCoO_2.5 bilayers			Type	A1 Journal article
Year	2019	Publication	Physical review B	Abbreviated Journal	Phys Rev B
Volume	99	Issue	2	Pages	024425
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Interface effect in complex oxide thin-film heterostructures lies at the vanguard of current research to design technologically relevant functionality and explore emergent physical phenomena. While most of the previous works focus on the perovskite/perovskite heterostructures, the study of perovskite/brownmillerite interfaces remains in its infancy. Here, we investigate spontaneously stabilized perovskite-ferromagnet (SrCoO3-delta)/brownmillerite-antiferromagnet (SrCoO2.5) bilayer with T-N > T-C and discover an unconventional interfacial magnetic exchange bias effect. From magnetometry investigations, it is rationalized that the observed effect stems from the interfacial ferromagnet/antiferromagnet coupling. The possibility for coupled ferromagnet/spin-glass interface engendering such effect is ruled out. Strikingly, a finite coercive field persists in the paramagnetic state of SrCoO3-delta,whereas the exchange bias field vanishes at T-C . We conjecture the observed effect to be due to the effective external quenched staggered field provided by the antiferromagnetic layer for the ferromagnetic spins at the interface. Our results not only unveil a paradigm to tailor the interfacial magnetic properties in oxide heterostructures without altering the cations at the interface, but also provide a purview to delve into the fundamental aspects of exchange bias in such unusual systems, paving a big step forward in thin-film magnetism.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000456481900003	Publication Date	2019-01-23
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	2	Open Access	OpenAccess
Notes	; We are grateful to Sachin Sarangi for his superb technical support during magnetic measurements. We thank Gopal Pradhan for fruitful discussion. We thank Zhicheng Zhong for reading the manuscript and for suggestions. We thank T. Som for extending laboratory facility. D.S. and B.C.B. acknowledge the financial support from Max-Planck Society through Max Planck Partner Group. S.G.B. acknowledges the INSPIRE Faculty Fellowship Programme (DSTO1899) for the financial support. ;			Approved	Most recent IF: 3.836
Call Number	UA @ admin @ c:irua:157562			Serial	5248
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Author	Das, S.; Rata, A.D.; Maznichenko, I., V; Agrestini, I.S.; Pippel, E.; Gauquelin, N.; Verbeeck, J.; Chen, K.; Valvidares, S.M.; Vasili, H.B.; Herrero-Martin, J.; Pellegrin, E.; Nenkov, K.; Herklotz, A.; Ernst, A.; Mertig, I.; Hu, Z.; Doerr, K.
Title	Low-field switching of noncollinear spin texture at La_0.7Sr_0.3MnO₃-SrRuO₃interfaces			Type	A1 Journal article
Year	2019	Publication	Physical review B	Abbreviated Journal	Phys Rev B
Volume	99	Issue	2	Pages	024416
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Interfaces of ferroic oxides can show complex magnetic textures which have strong impact on spintronics devices. This has been demonstrated recently for interfaces with insulating antiferromagnets such as BiFeO3. Here, noncollinear spin textures which can be switched in very low magnetic field are reported for conducting ferromagnetic bilayers of La0.7Sr0.3MnO3-SrRuO3 (LSMO-SRO). The magnetic order and switching are fundamentally different for bilayers coherently grown in reversed stacking sequence. The SRO top layer forms a persistent exchange spring which is antiferromagnetically coupled to LSMO and drives switching in low fields of a few milliteslas. Density functional theory reveals the crucial impact of the interface termination on the strength of Mn-Ru exchange coupling across the interface. The observation of an exchange spring agrees with ultrastrong coupling for the MnO2/SrO termination. Our results demonstrate low-field switching of noncollinear spin textures at an interface between conducting oxides, opening a pathway for manipulating and utilizing electron transport phenomena in controlled spin textures at oxide interfaces.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000455821400005	Publication Date	2019-01-15
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	19	Open Access	OpenAccess
Notes	; The research in Halle was supported by Deutsche Forschungsgemeinschaft (DFG), SFB 762 Functional Oxide Interfaces (Projects No. A9 and No. B1). K.C. benefited from support of the DFG (Project 600575). Discussions with M. Trassin, M. Ziese, H. M. Christen, E.-J. Guo, F. Grcondciel, M. Bibes, and H. N. Lee are gratefully acknowledged. N. G. and J. V. acknowledge funding under the GOA project “Solarpaint” of the University of Antwerp. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. ;			Approved	Most recent IF: 3.836
Call Number	UA @ admin @ c:irua:156717			Serial	5255
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Author	Kuo, C.-T.; Lin, S.-C.; Ghiringhelli, G.; Peng, Y.; De Luca, G.M.; Di Castro, D.; Betto, D.; Gehlmann, M.; Wijnands, T.; Huijben, M.; Meyer-Ilse, J.; Gullikson, E.; Kortright, J.B.; Vailionis, A.; Gauquelin, N.; Verbeeck, J.; Gerber, T.; Balestrino, G.; Brookes, N.B.; Braicovich, L.; Fadley, C.S.
Title	Depth-resolved resonant inelastic x-ray scattering at a superconductor/half-metallic-ferromagnet interface through standing wave excitation			Type	A1 Journal article
Year	2018	Publication	Physical review B	Abbreviated Journal	Phys Rev B
Volume	98	Issue	23	Pages	235146
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We demonstrate that combining standing wave (SW) excitation with resonant inelastic x-ray scattering (RIXS) can lead to depth resolution and interface sensitivity for studying orbital and magnetic excitations in correlated oxide heterostructures. SW-RIXS has been applied to multilayer heterostructures consisting of a superconductor La1.85Sr0.15CuO4 (LSCO) and a half-metallic ferromagnet La0.67Sr0.33MnO3 (LSMO). Easily observable SW effects on the RIXS excitations were found in these LSCO/LSMO multilayers. In addition, we observe different depth distribution of the RIXS excitations. The magnetic excitations are found to arise from the LSCO/LSMO interfaces, and there is also a suggestion that one of the dd excitations comes from the interfaces. SW-RIXS measurements of correlated-oxide and other multilayer heterostructures should provide unique layer-resolved insights concerning their orbital and magnetic excitations, as well as a challenge for RIXS theory to specifically deal with interface effects.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000454160800004	Publication Date	2018-12-21
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	5	Open Access
Notes	J.V. and N.G. acknowledge ˝ funding through the GOA project “Solarpaint” of the University of Antwerp. The microscope used in this work was partly funded by the Hercules Fund from the Flemish Government.			Approved	Most recent IF: 3.836
Call Number	UA @ admin @ c:irua:156784			Serial	5363
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Author	van der Torren, A.J.H.; Liao, Z.; Xu, C.; Gauquelin, N.; Yin, C.; Aarts, J.; van der Molen, S.J.
Title	Formation of a conducting LaAlO₃/SrTiO₃ interface studied by low-energy electron reflection during growth			Type	A1 Journal Article
Year	2017	Publication	Physical Review Materials	Abbreviated Journal	Phys. Rev. Materials
Volume	1	Issue	7	Pages	075001
Keywords	A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract	The two-dimensional electron gas occurring between the band insulators SrTiO 3 and LaAlO 3 continues to attract considerable interest, due to the possibility of dynamic control over the carrier density, and the ensuing phenomena such as magnetism and superconductivity. The formation of this conducting interface is sensitive to the growth conditions, but despite numerous investigations, there are still questions about the details of the physics involved. In particular, not much is known about the electronic structure of the growing LaAlO 3 layer at the growth temperature (around 800 ◦ C) in oxygen (pressure around 5 × 10 −5 mbar), since analysis techniques at these conditions are not readily available. We developed a pulsed laser deposition system inside a low-energy electron microscope in order to study this issue. The setup allows for layer-by-layer growth control and in-situ measurements of the angle-dependent electron reflection intensity, which can be used as a fingerprint of the electronic structure of the surface layers during growth. By using different substrate terminations and growth conditions we observe two families of reflectivity maps, which we can connect either to samples with an AlO 2 -rich surface and a conducting interface; or to samples with a LaO-rich surface and an insulating interface. Our observations emphasize that substrate termination and stoichiometry determine the electronic structure of the growing layer, and thereby the conductance of the interface.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000418770200003	Publication Date	2017-12-06
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links
Impact Factor		Times cited	2	Open Access	Not_Open_Access
Notes	Nederlandse Organisatie voor Wetenschappelijk Onderzoek; Fonds Wetenschappelijk Onderzoek, G.0044.13N ; European Cooperation in Science and Technology, MP 1308 ; We want to acknowledge Ruud Tromp, Daniel Gee- len, Johannes Jobst, Regina Dittmann, Gert Jan Koster, Guus Rijnders and Jo Verbeek for discussions and ad- vice and Ruud van Egmond and Marcel Hesselberth for technical assistance. This work was supported by the Netherlands Organization for Scientific Research (NWO) by means of an ”NWO Groot” grant and by the Leiden- Delft Consortium NanoFront. The work is part of the re- search programmes NWOnano and DESCO, which are fi- nanced by NWO. N.G. acknowledges funding through the GOA project “Solarpaint” of the University of Antwerp and from the FWO project G.0044.13N (Charge order- ing). The microscope used in this work was partly funded by the Hercules Fund from the Flemish Government. We would also like to acknowledge networking support by the COST Action MP 1308 (COST TO-BE).			Approved	Most recent IF: NA
Call Number	EMAT @ emat @			Serial	4903
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Author	Zhang, H.; Gauquelin, N.; McMahon, C.; Hawthorn, D.G.; Botton, G.A.; Wei, J.Y.T.
Title	Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films			Type	A1 Journal article
Year	2018	Publication	Physical review materials	Abbreviated Journal
Volume	2	Issue	3	Pages	033803
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	It is known that solid-state reaction in high-pressure oxygen can stabilize high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend this superoxygenation concept of synthesis to thin films which, due to their large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial thin films of YBa2Cu3O7-delta grown by pulsed laser deposition are annealed at up to 700 atm O-2 and 900 degrees C, in conjunction with Cu enrichment by solid-state diffusion. The films show the clear formation of Y2Ba4Cu7O15-delta and Y2Ba4Cu8O16 as well as regions of YBa2Cu5O9-delta and YBa2Cu6O10-delta phases, according to scanning transmission electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Similarly annealed YBa2Cu3O7-delta powders show no phase conversion. Our results demonstrate a route of synthesis towards discovering more complex phases of cuprates and other superconducting oxides.
Address
Corporate Author				Thesis
Publisher	American Physical Society	Place of Publication	College Park, Md	Editor
Language		Wos	000428244900004	Publication Date	2018-03-26
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	2	Open Access	Not_Open_Access
Notes	; This work is supported by NSERC, CFI-OIT, and CIFAR. The electron microscopy work was carried out at the Canadian Centre for Electron Microscopy, a National Facility supported by the Canada Foundation for Innovation under the Major Science Initiative program, McMaster University, and NSERC. The XAS work was performed at the Canadian Light Source, which is supported by NSERC, NRC, CIHR, and the University of Saskatchewan. ;			Approved	Most recent IF: NA
Call Number	UA @ lucian @ c:irua:150829			Serial	4982
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Author	Yin, C.; Krishnan, D.; Gauquelin, N.; Verbeeck, J.; Aarts, J.
Title	Controlling the interfacial conductance in LaAlO₃/SrTiO₃ in 90 degrees off-axis sputter deposition			Type	A1 Journal article
Year	2019	Publication	Physical review materials	Abbreviated Journal
Volume	3	Issue	3	Pages	034002
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We report on the fabrication of conducting interfaces between LaAlO3 and SrTiO3 by 90 degrees off-axis sputtering in an Ar atmosphere. At a growth pressure of 0.04 mbar the interface is metallic, with a carrier density of the order of 1 x 10(13) cm(-2) at 3 K. By increasing the growth pressure, we observe an increase of the out-of-plane lattice constants of the LaAlO3 films while the in-plane lattice constants do not change. Also, the low-temperature sheet resistance increases with increasing growth pressure, leading to an insulating interface when the growth pressure reaches 0.10 mbar. We attribute the structural variations to an increase of the La/Al ratio, which also explains the transition from metallic behavior to insulating behavior of the interfaces. Our research shows that the control which is furnished by the Ar pressure makes sputtering as versatile a process as pulsed laser deposition, and emphasizes the key role of the cation stoichiometry of LaAlO3 in the formation of the conducting interface.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000461077100002	Publication Date	2019-03-12
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.926	Times cited	4	Open Access	Not_Open_Access
Notes	; We thank Nikita Lebedev, Aymen Ben Hamida, and Prateek Kumar for useful discussions and Giordano Mattoni, Jun Wang, Vincent Joly, and Hozanna Miro for their technical assistance. We also thank Jean-Marc Triscone and his group for sharing their design of the sputtering system with us. This work is part of the FOM research programme DESCO with Project No. 149, which is (partly) financed by the Netherlands Organisation for Scientific Research (NWO). C.Y. is supported by China Scholarship Council (CSC) with Grant No. 201508110214. N.G., D.K., and J.V. acknowledge financial support from the GOA project “Solarpaint” of the University of Antwerp. ;			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:158547			Serial	5243
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Author	Chen, B.; Gauquelin, N.; Reith, P.; Halisdemir, U.; Jannis, D.; Spreitzer, M.; Huijben, M.; Abel, S.; Fompeyrine, J.; Verbeeck, J.; Hilgenkamp, H.; Rijnders, G.; Koster, G.
Title	Thermal-strain-engineered ferromagnetism of LaMnO3/SrTiO3 heterostructures grown on silicon			Type	A1 Journal article
Year	2020	Publication	Physical review materials	Abbreviated Journal	Phys. Rev. Materials
Volume	4	Issue	2	Pages	024406
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The integration of oxides on Si remains challenging, which largely hampers the practical applications of oxide-based electronic devices with superior performance. Recently, LaMnO3/SrTiO3 (LMO/STO) heterostructures have gained renewed interest for the debating origin of the ferromagnetic-insulating ground state as well as for their spin-filter applications. Here we report on the structural and magnetic properties of high-quality LMO/STO heterostructures grown on silicon. The chemical abruptness across the interface was investigated by atomic-resolution scanning transmission electron microscopy. The difference in the thermal expansion coefficients between LMO and Si imposed a large biaxial tensile strain to the LMO film, resulting in a tetragonal structure with c/a∼ 0.983. Consequently, we observed a significantly suppressed ferromagnetism along with an enhanced coercive field, as compared to the less distorted LMO film (c/a∼1.004) grown on STO single crystal. The results are discussed in terms of tensile-strain enhanced antiferromagnetic instabilities. Moreover, the ferromagnetism of LMO on Si sharply disappeared below a thickness of 5 unit cells, in agreement with the LMO/STO case, pointing to a robust critical behavior irrespective of the strain state. Our results demonstrate that the growth of oxide films on Si can be a promising way to study the tensile-strain effects in correlated oxides, and also pave the way towards the integration of multifunctional oxides on Si with atomic-layer control.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000513552900003	Publication Date	2020-02-12
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.4	Times cited	6	Open Access	Not_Open_Access
Notes	Nederlandse Organisatie voor Wetenschappelijk Onderzoek; Universiteit Antwerpen; Vlaamse regering; Fonds Wetenschappelijk Onderzoek, G093417N ; Javna Agencija za Raziskovalno Dejavnost RS, J2-9237 P2-0091 ; European Commission, H2020-ICT-2016-1-732642 ;			Approved	Most recent IF: 3.4; 2020 IF: NA
Call Number	EMAT @ emat @c:irua:167782			Serial	6375
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Author	Araizi-Kanoutas, G.; Geessinck, J.; Gauquelin, N.; Smit, S.; Verbeek, X.H.; Mishra, S.K.; Bencok, P.; Schlueter, C.; Lee, T.-L.; Krishnan, D.; Fatermans, J.; Verbeeck, J.; Rijnders, G.; Koster, G.; Golden, M.S.
Title	Co valence transformation in isopolar LaCoO3/LaTiO3 perovskite heterostructures via interfacial engineering			Type	A1 Journal article
Year	2020	Publication	Physical review materials	Abbreviated Journal	Phys. Rev. Materials
Volume	4	Issue	2	Pages	026001
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We report charge transfer up to a single electron per interfacial unit cell across nonpolar heterointerfaces from the Mott insulator LaTiO3 to the charge transfer insulator LaCoO3. In high-quality bi- and trilayer systems grown using pulsed laser deposition, soft x-ray absorption, dichroism, and scanning transmission electron microscopy-electron energy loss spectroscopy are used to probe the cobalt-3d electron count and provide an element-specific investigation of the magnetic properties. The experiments show the cobalt valence conversion is active within 3 unit cells of the heterointerface, and able to generate full conversion to 3d7 divalent Co, which displays a paramagnetic ground state. The number of LaTiO3/LaCoO3 interfaces, the thickness of an additional, electronically insulating “break” layer between the LaTiO3 and LaCoO3, and the LaCoO3 film thickness itself in trilayers provide a trio of control knobs for average charge of the cobalt ions in LaCoO3, illustrating the efficacy of O−2p band alignment as a guiding principle for property design in complex oxide heterointerfaces.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000513551200007	Publication Date	2020-02-10
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.4	Times cited	13	Open Access	OpenAccess
Notes	Nederlandse Organisatie voor Wetenschappelijk Onderzoek; Universiteit Antwerpen; Horizon 2020, 730872 ; Department of Science and Technology, Ministry of Science and Technology, SR/NM/Z-07/2015 ; Jawaharlal Nehru Centre for Advanced Scientific Research;			Approved	Most recent IF: 3.4; 2020 IF: NA
Call Number	EMAT @ emat @c:irua:167787			Serial	6376
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Author	Lin, S.-C.; Kuo, C.-T.; Shao, Y.-C.; Chuang, Y.-D.; Geessinck, J.; Huijben, M.; Rueff, J.-P.; Graff, I.L.; Conti, G.; Peng, Y.; Bostwick, A.; Gullikson, E.; Nemsak, S.; Vailionis, A.; Gauquelin, N.; Verbeeck, J.; Ghiringhelli, G.; Schneider, C.M.; Fadley, C.S.
Title	Two-dimensional electron systems in perovskite oxide heterostructures : role of the polarity-induced substitutional defects			Type	A1 Journal article
Year	2020	Publication	Physical review materials	Abbreviated Journal
Volume	4	Issue	11	Pages	115002
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The discovery of a two-dimensional electron system (2DES) at the interfaces of perovskite oxides such as LaAlO3 and SrTiO3 has motivated enormous efforts in engineering interfacial functionalities with this type of oxide heterostructures. However, the fundamental origins of the 2DES are still not understood, e.g., the microscopic mechanisms of coexisting interface conductivity and magnetism. Here we report a comprehensive spectroscopic investigation on the depth profile of 2DES-relevant Ti 3d interface carriers using depthand element-specific techniques like standing-wave excited photoemission and resonant inelastic scattering. We found that one type of Ti 3d interface carriers, which give rise to the 2DES are located within three unit cells from the n-type interface in the SrTiO3 layer. Unexpectedly, another type of interface carriers, which are polarity-induced Ti-on-Al antisite defects, reside in the first three unit cells of the opposing LaAlO3 layer (similar to 10 angstrom). Our findings provide a microscopic picture of how the localized and mobile Ti 3d interface carriers distribute across the interface and suggest that the 2DES and 2D magnetism at the LaAlO3/SrTiO3 interface have disparate explanations as originating from different types of interface carriers.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000592432200004	Publication Date	2020-11-20
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.4	Times cited	7	Open Access	OpenAccess
Notes	; We thank G. M. De Luca and L. Braicovich for discussions. Charles S. Fadley was deceased on August 1, 2019. We are grateful for his significant contributions to this work. We thank Advanced Light Source for the access to Beamline 8.0.3 (qRIXS) via Proposal No. 09892 and beamline 7.0.2 (MAESTRO) via Proposal No. RA-00291 that contributed to the results presented here. We thank synchrotron SOLEIL (via Proposal No. 99180118) for the access to Beamline GALAXIES. This work was supported by the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231 (Advanced Light Source), and by DOE Contract No. DE-SC0014697 through the University of California, Davis (S.-C.L., C.-T.K, and C.S.F.), and from the Julich Research Center, Peter Grunberg Institute, PGI-6. I. L. G. wishes to thank Brazilian scientific agencies CNPQ (Project No. 200789/2017-1) and CAPES (CAPES-PrInt-UFPR) for their financial support. J.V. and N.G. acknowledge funding from the Geconcentreerde Onderzoekacties (GOA) project “Solarpaint” of the University of Antwerp and the European Union's horizon 2020 research and innovation program ES-TEEM3 under grant agreement no 823717. The Qu-Ant-EM microscope used in this study was partly funded by the Hercules fund from the Flemish Government. ; esteem3TA; esteem3reported			Approved	Most recent IF: 3.4; 2020 IF: NA
Call Number	UA @ admin @ c:irua:174316			Serial	6713
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Author	Lebedev, N.; Huang, Y.; Rana, A.; Jannis, D.; Gauquelin, N.; Verbeeck, J.; Aarts, J.
Title	Resistance minimum in LaAlO₃/Eu_1-xLa_xTiO₃/SrTiO₃ heterostructures			Type	A1 Journal article
Year	2022	Publication	Physical review materials	Abbreviated Journal
Volume	6	Issue	7	Pages	075003-75010
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	In this paper we study LaAlO3/Eu1-xLaxTiO3/SrTiO3 structures with nominally x = 0, 0.1 and different thicknesses of the Eu1-xLaxTiO3 layer. We observe that both systems have many properties similar to previously studied LaAlO3/EuTiO3/SrTiO3 and other oxide interfaces, such as the formation of a two-dimensional electron liquid for two unit cells of Eu1-xLaxTiO3; a metal-insulator transition driven by the increase in thickness of the Eu1-xLaxTiO3 layer; the presence of an anomalous Hall effect when driving the systems above the Lifshitz point with a back-gate voltage; and a minimum in the temperature dependence of the sheet resistance below the Lifshitz point in the one-band regime, which becomes more pronounced with increasing negative gate voltage. However, and notwithstanding the likely presence of magnetism in the system, we do not attribute that minimum to the Kondo effect, but rather to the properties of the SrTiO3 crystal and the inevitable effects of charge trapping when using back gates.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000834035300001	Publication Date	2022-07-12
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	3.4	Times cited		Open Access	OpenAccess
Notes	N.L. and J.A. gratefully acknowledge the financial support of the research program DESCO, which is financed by the Netherlands Organisation for Scientific Research (NWO). J.V. and N.G. acknowledge funding from the Geconcentreerde Onderzoekacties (GOA) project “Solarpaint” of the University of Antwerp and the European Union’s horizon 2020 research and innovation programme under grant agreement №823717 – ESTEEM3. The QuAnt-EM microscope used in this study was partly funded by the Hercules fund from the Flemish Government. The authors want to thank M. Stehno, G. Koster, and F.J.G. Roesthuis for useful discussions.; esteem3reported; esteem3TA			Approved	Most recent IF: 3.4
Call Number	UA @ admin @ c:irua:189674			Serial	7094
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Author	Samal, D.; Gauquelin, N.; Takamura, Y.; Lobato, I.; Arenholz, E.; Van Aert, S.; Huijben, M.; Zhong, Z.; Verbeeck, J.; Van Tendeloo, G.; Koster, G.
Title	Unusual structural rearrangement and superconductivity in infinite layer cuprate superlattices			Type	A1 Journal article
Year	2023	Publication	Physical review materials	Abbreviated Journal
Volume	7	Issue	5	Pages	054803
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	001041792100007	Publication Date	2023-05-30
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	3.4	Times cited		Open Access	OpenAccess
Notes	Air Force Office of Scientific Research; European Office of Aerospace Research and Development, FA8655-10-1-3077 ; Office of Science, DE-AC02-05CH11231 ; National Science Foundation, DMR-1745450 ; Seventh Framework Programme, 278510 ; Bijzonder Onderzoeksfonds UGent;			Approved	Most recent IF: 3.4; 2023 IF: NA
Call Number	EMAT @ emat @c:irua:196973			Serial	8790
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Author	Herzog, M.J.; Gauquelin, N.; Esken, D.; Verbeeck, J.; Janek, J.
Title	Increased Performance Improvement of Lithium-Ion Batteries by Dry Powder Coating of High-Nickel NMC with Nanostructured Fumed Ternary Lithium Metal Oxides			Type	A1 Journal article
Year	2021	Publication	ACS applied energy materials	Abbreviated Journal	ACS Appl. Energy Mater.
Volume	4	Issue	9	Pages	8832-8848
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Dry powder coating is an effective approach to protect the surfaces of layered cathode active materials (CAMs) in lithium-ion batteries. Previous investigations indicate an incorporation of lithium ions in fumed Al2O3, ZrO2, and TiO2 coatings on LiNi0.7Mn0.15Co0.15O2 during cycling, improving the cycling performance. Here, this coating approach is transferred for the first time to fumed ternary LiAlO2, Li4Zr3O8, and Li4Ti5O12 and directly compared with their lithium-free equivalents. All materials could be processed equally and their nanostructured small aggregates accumulate on the CAM surfaces to quite homogeneous coating layers with a certain porosity. The LiNixMnyCozO2 (NMC) coated with lithium-containing materials shows an enhanced improvement in overall capacity, capacity retention, rate performance, and polarization behavior during cycling, compared to their lithium-free analogues. The highest rate performance was achieved with the fumed ZrO2 coating, while the best long-term cycling stability with the highest absolute capacity was obtained for the fumed LiAlO2-coated NMC. The optimal coating agent for NMC to achieve a balanced system is fumed Li4Ti5O12, providing a good compromise between high rate capability and good capacity retention. The coating agents prevent CAM particle cracking and degradation in the order LiAlO2 ≈ Al2O3 > Li4Ti5O12 > Li4Zr3O8 > ZrO2 > TiO2. A schematic model for the protection and electrochemical performance enhancement of high-nickel NMC with fumed metal oxide coatings is sketched. It becomes apparent that physical and chemical characteristics of the coating significantly influence the performance of NMC. A high degree of coating-layer porosity is favorable for the rate capability, while a high coverage of the surface, especially in vulnerable grain boundaries, enhances the long-term cycling stability and improves the cracking behavior of NMCs. While zirconium-containing coatings possess the best chemical properties for high rate performances, aluminum-containing coatings feature a superior chemical nature to protect high-nickel NMCs.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000703338600018	Publication Date	2021-09-27
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2574-0962	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	15	Open Access	OpenAccess
Notes	For his support in scanning electron microscopy analysis, the authors thank Erik Peldszus. N. G. and J. V. acknowledge funding from GOA project “Solarpaint” of the University of Antwerp and from the Flemish Research Fund (FWO) project G0F1320N. The Qu-Ant-EM microscope and the direct electron detector were partly funded by the Hercules fund from the Flemish Government			Approved	Most recent IF: NA
Call Number	EMAT @ emat @c:irua:183949			Serial	6823
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Author	Joy, R.M.; Pobedinskas, P.; Bourgeois, E.; Chakraborty, T.; Goerlitz, J.; Herrmann, D.; Noel, C.; Heupel, J.; Jannis, D.; Gauquelin, N.; D'Haen, J.; Verbeeck, J.; Popov, C.; Houssiau, L.; Becher, C.; Nesladek, M.; Haenen, K.
Title	Photoluminescence of germanium-vacancy centers in nanocrystalline diamond films : implications for quantum sensing applications			Type	A1 Journal article
Year	2024	Publication	ACS applied nano materials	Abbreviated Journal
Volume	7	Issue	4	Pages	3873-3884
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Point defects in diamond, promising candidates for nanoscale pressure- and temperature-sensing applications, are potentially scalable in polycrystalline diamond fabricated using the microwave plasma-enhanced chemical vapor deposition (MW PE CVD) technique. However, this approach introduces residual stress in the diamond films, leading to variations in the characteristic zero phonon line (ZPL) of the point defect in diamond. Here, we report the effect of residual stress on germanium-vacancy (GeV) centers in MW PE CVD nanocrystalline diamond (NCD) films fabricated using single crystal Ge as the substrate and solid dopant source. GeV ensemble formation indicated by the zero phonon line (ZPL) at similar to 602 nm is confirmed by room temperature (RT) photoluminescence (PL) measurements. PL mapping results show spatial nonuniformity in GeV formation along with other defects, including silicon-vacancy centers in the diamond films. The residual stress in NCD results in shifts in the PL peak positions. By estimating a stress shift coefficient of (2.9 +/- 0.9) nm/GPa, the GeV PL peak position in the NCD film is determined to be between 598.7 and 603.2 nm. A larger ground state splitting due to the strain on a GeV-incorporated NCD pillar at a low temperature (10 K) is also reported. We also report the observation of intense ZPLs at RT that in some cases could be related to low Ge concentration and the surrounding crystalline environment. In addition, we also observe thicker microcrystalline diamond (MCD) films delaminate from the Ge substrate due to film residual stress and graphitic phase at the diamond/Ge substrate interface (confirmed by electron energy loss spectroscopy). Using this approach, a free-standing color center incorporated MCD film with dimensions up to 1 x 1 cm(2) is fabricated. Qualitative analysis using time-of-flight secondary ion mass spectroscopy reveals the presence of impurities, including Ge and silicon, in the MCD film. Our experimental results will provide insights into the scalability of GeV fabrication using the MW PE CVD technique and effectively implement NCD-based nanoscale-sensing applications.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	001164609600001	Publication Date	2024-02-15
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2574-0970	ISBN		Additional Links	UA library record; WoS full record
Impact Factor	5.9	Times cited		Open Access
Notes				Approved	Most recent IF: 5.9; 2024 IF: NA
Call Number	UA @ admin @ c:irua:204826			Serial	9164
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Author	Poulain, R.; Lumbeeck, G.; Hunka, J.; Proost, J.; Savolainen, H.; Idrissi, H.; Schryvers, D.; Gauquelin, N.; Klein, A.
Title	Electronic and chemical properties of nickel oxide thin films and the intrinsic defects compensation mechanism			Type	A1 Journal article
Year	2022	Publication	ACS applied electronic materials	Abbreviated Journal
Volume	4	Issue	6	Pages	2718-2728
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Although largely studied, contradictory results on nickel oxide (NiO) properties can be found in the literature. We herein propose a comprehensive study that aims at leveling contradictions related to NiO materials with a focus on its conductivity, surface properties, and the intrinsic charge defects compensation mechanism with regards to the conditions preparation. The experiments were performed by in situ photo-electron spectroscopy, electron energy loss spectroscopy, and optical as well as electrical measurements on polycrystalline NiO thin films prepared under various preparation conditions by reactive sputtering. The results show that surface and bulk properties were strongly related to the deposition temperature with in particular the observation of Fermi level pinning, high work function, and unstable oxygen-rich grain boundaries for the thin films produced at room temperature but not at high temperature (>200 degrees C). Finally, this study provides substantial information about surface and bulk NiO properties enabling to unveil the origin of the high electrical conductivity of room temperature NiO thin films and also for supporting a general electronic charge compensation mechanism of intrinsic defects according to the deposition temperature.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000819431200001	Publication Date	2022-06-07
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2637-6113	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited		Open Access	Not_Open_Access
Notes				Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:189555			Serial	7081
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Author	Birkholzer, Y.A.; Sotthewes, K.; Gauquelin, N.; Riekehr, L.; Jannis, D.; van der Minne, E.; Bu, Y.; Verbeeck, J.; Zandvliet, H.J.W.; Koster, G.; Rijnders, G.
Title	High-strain-induced local modification of the electronic properties of VO₂ thin films			Type	A1 Journal article
Year	2022	Publication	ACS applied electronic materials	Abbreviated Journal
Volume	4	Issue	12	Pages	6020-6028
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Vanadium dioxide (VO2) is a popular candidate for electronic and optical switching applications due to its well-known semiconductor-metal transition. Its study is notoriously challenging due to the interplay of long- and short-range elastic distortions, as well as the symmetry change and the electronic structure changes. The inherent coupling of lattice and electronic degrees of freedom opens the avenue toward mechanical actuation of single domains. In this work, we show that we can manipulate and monitor the reversible semiconductor-to-metal transition of VO2 while applying a controlled amount of mechanical pressure by a nanosized metallic probe using an atomic force microscope. At a critical pressure, we can reversibly actuate the phase transition with a large modulation of the conductivity. Direct tunneling through the VO2-metal contact is observed as the main charge carrier injection mechanism before and after the phase transition of VO2. The tunneling barrier is formed by a very thin but persistently insulating surface layer of the VO2. The necessary pressure to induce the transition decreases with temperature. In addition, we measured the phase coexistence line in a hitherto unexplored regime. Our study provides valuable information on pressure-induced electronic modifications of the VO2 properties, as well as on nanoscale metal-oxide contacts, which can help in the future design of oxide electronics.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000890974900001	Publication Date	2022-11-18
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2637-6113	ISBN		Additional Links	UA library record; WoS full record
Impact Factor		Times cited	2	Open Access	OpenAccess
Notes	This work received financial support from the project Green ICT (grant number 400.17.607) of the research program NWA, which is financed by the Dutch Research Council (NWO), Research Foundation Flanders (FWO grant number G0F1320N), and the European Union’s Horizon 2020 research and innovation program within a contract for Integrating Activities for Advanced Communities (grant number 823717 − ESTEEM3). The K2 camera was funded through the Research Foundation Flanders (FWO-Hercules grant number G0H4316N – “Direct electron detector for soft matter TEM”).; esteem3reported; esteem3jra			Approved	Most recent IF: NA
Call Number	UA @ admin @ c:irua:192712			Serial	7309
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Author	Groenendijk, D.J.; Autieri, C.; van Thiel, T.C.; Brzezicki, W.; Hortensius, J.R.; Afanasiev, D.; Gauquelin, N.; Barone, P.; van den Bos, K.H.W.; van Aert, S.; Verbeeck, J.; Filippetti, A.; Picozzi, S.; Cuoco, M.; Caviglia, A.D.
Title	Berry phase engineering at oxide interfaces			Type	A1 Journal article
Year	2020	Publication		Abbreviated Journal	Phys. Rev. Research
Volume	2	Issue	2	Pages	023404
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Three-dimensional strontium ruthenate (SrRuO3) is an itinerant ferromagnet that features Weyl points acting as sources of emergent magnetic fields, anomalous Hall conductivity, and unconventional spin dynamics. Integrating SrRuO3 in oxide heterostructures is potentially a novel route to engineer emergent electrodynamics, but its electronic band topology in the two-dimensional limit remains unknown. Here we show that ultrathin SrRuO3 exhibits spin-polarized topologically nontrivial bands at the Fermi energy. Their band anticrossings show an enhanced Berry curvature and act as competing sources of emergent magnetic fields. We control their balance by designing heterostructures with symmetric (SrTiO3/SrRuO3/SrTiO3 and SrIrO3/SrRuO3/SrIrO3) and asymmetric interfaces (SrTiO3/SrRuO3/SrIrO3). Symmetric structures exhibit an interface-tunable single-channel anomalous Hall effect, while ultrathin SrRuO3 embedded in asymmetric structures shows humplike features consistent with multiple Hall contributions. The band topology of two-dimensional SrRuO3 proposed here naturally accounts for these observations and harmonizes a large body of experimental results.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000603642700008	Publication Date	2020-06-25
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2643-1564	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor		Times cited	58	Open Access	OpenAccess
Notes	Nederlandse Organisatie voor Wetenschappelijk Onderzoek; Fonds Wetenschappelijk Onderzoek; European Research Council; Horizon 2020, 677458 770887 731473 ; Fondazione Cariplo, 2013-0726 ; Narodowe Centrum Nauki, 2016/23/B/ST3/00839 ; Fundacja na rzecz Nauki Polskiej; Universiteit Antwerpen; Vlaamse regering;			Approved	Most recent IF: NA
Call Number	EMAT @ emat @c:irua:172462			Serial	6401
Permanent link to this record