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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 (up)
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.
Address
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 Scalise, E.; Houssa, M.; Cinquanta, E.; Grazianetti, C.; van den Broek, B.; Pourtois, G.; Stesmans, A.; Fanciulli, M.; Molle, A.
Title Engineering the electronic properties of silicene by tuning the composition of MoX2 and GaX (X = S,Se,Te) chalchogenide templates Type A1 Journal article
Year 2014 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 1 Issue 1 Pages 011010
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract By using first-principles simulations, we investigate the interaction of a 2D silicon layer with two classes of chalcogenide-layered compounds, namely MoX2 and GaX (X = S, Se, Te). A rather weak (van der Waals) interaction between the silicene layers and the chalcogenide layers is predicted. We found that the buckling of the silicene layer is correlated to the lattice mismatch between the silicene layer and the MoX2 or GaX template. The electronic properties of silicene on these different templates largely depend on the buckling of the silicene layer: highly buckled silicene on MoS2 is predicted to be metallic, while low buckled silicene on GaS and GaSe is predicted to be semi-metallic, with preserved Dirac cones at the K points. These results indicate new routes for artificially engineering silicene nanosheets, providing tailored electronic properties of this 2D layer on non-metallic substrates. These non-metallic templates also open the way to the possible integration of silicene in future nanoelectronic devices.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000353649900011 Publication Date 2014-05-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 49 Open Access
Notes Approved Most recent IF: 6.937; 2014 IF: NA
Call Number UA @ lucian @ c:irua:126032 Serial 1048
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Author Van Duppen, B.; Tomadin, A.; Grigorenko, A.N.; Polini, M.
Title Current-induced birefringent absorption and non-reciprocal plasmons in graphene Type A1 Journal article
Year 2016 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 3 Issue 3 Pages 015011
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present extensive calculations of the optical and plasmonic properties of a graphene sheet carrying a dc current. By calculating analytically the density-density response function of current-carrying states at finite temperature, we demonstrate that an applied dc current modifies the Pauli blocking mechanism and that absorption acquires a birefringent character with respect to the angle between the in-plane light polarization and current flow. Employing the random phase approximation at finite temperature, we show that graphene plasmons display a degree of non-reciprocity and collimation that can be tuned with the applied current. We discuss the possibility to measure these effects.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000373936300031 Publication Date 2016-02-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 5 Open Access
Notes This work was supported by the EC under the Graphene Flagship program (contract no. CNECT- ICT-604391) and MIUR through the program ‘Pro- getti Premiali 2012’ – Project ‘ABNANOTECH’. B.V. D. wishes to thank the Scuola Normale Superiore (Pisa, Italy) for the kind hospitality while this work was carried out and Research Foundation Flanders (FWO- Vl) for a PhD Fellowship. Approved Most recent IF: 6.937
Call Number c:irua:131900 c:irua:131900 Serial 4017
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Author Leenaerts, O.; Vercauteren, S.; Schoeters, B.; Partoens, B.
Title System-size dependent band alignment in lateral two-dimensional heterostructures Type A1 Journal article
Year 2016 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 3 Issue 3 Pages 025012
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The electronic band alignment in semiconductor heterostructures is a key factor for their use in electronic applications. The alignment problem has been intensively studied for bulk systems but is less well understood for low-dimensional heterostructures. In this work we investigate the alignment in two-dimensional lateral heterostructures. First-principles calculations are used to show that the electronic band offset depends crucially on the width and thickness of the heterostructure slab. The particular heterostructures under study consist of thin hydrogenated and fluorinated diamond slabs which are laterally joined together. Two different limits for the band offset are observed. For infinitely wide heterostructures the vacuum potential above the two materials is aligned leading to a large step potential within the heterostructure. For infinitely thick heterostructure slabs, on the other hand, there is no potential step in the heterostructure bulk, but a large potential step in the vacuum region above the heterojunction is observed. The band alignment in finite systems depends on the particular dimensions of the system. These observations are shown to result from an interface dipole at the heterojunction that tends to align the band structures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000378571400032 Publication Date 2016-04-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 19 Open Access
Notes This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO-Vl). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government— department EWI. Approved Most recent IF: 6.937
Call Number c:irua:132792 c:irua:132792 Serial 4055
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Author Ozaydin, H.D.; Sahin, H.; Kang, J.; Peeters, F.M.; Senger, R.T.
Title Electronic and magnetic properties of 1T-TiSe2 nanoribbons Type A1 Journal article
Year 2015 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 2 Issue 2 Pages 044002
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Motivated by the recent synthesis of single layer TiSe2, we used state-of-the-art density functional theory calculations, to investigate the structural and electronic properties of zigzag and armchair-edged nanoribbons (NRs) of this material. Our analysis reveals that, differing from ribbons of other ultra-thin materials such as graphene, TiSe2 NRs have some distinctive properties. The electronic band gap of the NRs decreases exponentially with the width and vanishes for ribbons wider than 20 angstrom. For ultranarrow zigzag-edged NRs we find odd-even oscillations in the band gap width, although their band structures show similar features. Moreover, our detailed magnetic-ground-state analysis reveals that zigzag and armchair edged ribbons have non-magnetic ground states. Passivating the dangling bonds with hydrogen at the edges of the structures influences the band dispersion. Our results shed light on the characteristic properties of T phase NRs of similar crystal structures.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000368936600005 Publication Date 2015-10-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 20 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem foundation of the Flemish government. Computational resources were provided by TUBITAK ULAK-BIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). HS is supported by a FWO Pegasus Long Marie Curie Fellowship. JK is supported by a FWO Pegasus Short Marie Curie Fellowship. HDO, HS and RTS acknowledge the support from TUBITAK through project 114F397. ; Approved Most recent IF: 6.937; 2015 IF: NA
Call Number UA @ lucian @ c:irua:131602 Serial 4169
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Author Van der Donck, M.; De Beule, C.; Partoens, B.; Peeters, F.M.; Van Duppen, B.
Title Piezoelectricity in asymmetrically strained bilayer graphene Type A1 Journal article
Year 2016 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 3 Issue 3 Pages 035015
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We study the electronic properties of commensurate faulted bilayer graphene by diagonalizing the one-particle Hamiltonian of the bilayer system in a complete basis of Bloch states of the individual graphene layers. Our novel approach is very general and can be easily extended to any commensurate graphene-based heterostructure. Here, we consider three cases: (i) twisted bilayer graphene, (ii) bilayer graphene where triaxial stress is applied to one layer and (iii) bilayer graphene where uniaxial stress is applied to one layer. We show that the resulting superstructures can be divided into distinct classes, depending on the twist angle or the magnitude of the induced strain. The different classes are distinguished from each other by the interlayer coupling mechanism, resulting in fundamentally different low-energy physics. For the cases of triaxial and uniaxial stress, the individual graphene layers tend to decouple and we find significant charge transfer between the layers. In addition, this piezoelectric effect can be tuned by applying a perpendicular electric field. Finally, we show how our approach can be generalized to multilayer systems.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000384072500003 Publication Date 2016-08-31
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 10 Open Access
Notes ; This work was supported by the Research Foundation-Flanders (FWO-Vl) through aspirant research grants to MVDD, CDB, and BVD. ; Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:137203 Serial 4361
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Author van den Broek, B.; Houssa, M.; Scalise, E.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Two-dimensional hexagonal tin : ab initio geometry, stability, electronic structure and functionalization Type A1 Journal article
Year 2014 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 1 Issue Pages 021004
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract We study the structural, mechanical and electronic properties of the two-dimensional (2D) allotrope of tin: tinene/stanene using first-principles calculation within density functional theory, implemented in a set of computer codes. Continuing the trend of the group-IV 2D materials graphene, silicene and germanene; tinene is predicted to have a honeycomb lattice with lattice parameter of a(0) = 4.62 angstrom and a buckling of d(0) = 0.92 angstrom. The electronic dispersion shows a Dirac cone with zero gap at the Fermi energy and a Fermi velocity of v(F) = 0.97 x 10(6) m s(-1); including spin-orbit coupling yields a bandgap of 0.10 eV. The monolayer is thermally stable up to 700 K, as indicated by first-principles molecular dynamics, and has a phonon dispersion without imaginary frequencies. We explore applied electric field and applied strain as functionalization mechanisms. Combining these two mechanisms allows for an induced bandgap up to 0.21 eV, whilst retaining the linear dispersion, albeit with degraded electronic transport parameters.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000353650400004 Publication Date 2014-08-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 58 Open Access
Notes Approved Most recent IF: 6.937; 2014 IF: NA
Call Number UA @ lucian @ c:irua:134432 Serial 4530
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Author van den Broek, B.; Houssa, M.; Iordanidou, K.; Pourtois, G.; Afanas'ev, V.V.; Stesmans, A.
Title Functional silicene and stanene nanoribbons compared to graphene: electronic structure and transport Type A1 Journal article
Year 2016 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 3 Issue 1 Pages 015001
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Since the advent of graphene, other 2D materials have garnered interest; notably the single element materials silicene, germanene, and stanene. Weinvestigate the ballistic current-voltage (I-V) characteristics of armchair silicene and stanene armchair nanoribbons (AXNRs with X = Si, Sn) using a combination of density functional theory and non-equilibrium Green's functions. The impact of out-of-plane electric field and in-plane uniaxial strain on the ribbon geometries, electronic structure, and (I-V)s are considered and contrasted with graphene. Since silicene and stanene are sp(2)/sp(3) buckled layers, the electronic structure can be tuned by an electric field that breaks the sublattice symmetry, an effect absent in graphene. This decreases the current by similar to 50% for Sn, since it has the largest buckling. Uniaxial straining of the ballistic channel affects the AXNR electronic structure in multiple ways: it changes the bandgap and associated effective carrier mass, and creates a local buckling distortion at the lead-channel interface which induces a interface dipole. Due to the increasing sp(3) hybridization character with increasing element mass, large reconstructions rectify the strained systems, an effect absent in sp(2) bonded graphene. This results in a smaller strain effect on the current: a decrease of 20% for Sn at 15% tensile strain compared to a similar to 75% decrease for C.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000373936300021 Publication Date 2016-01-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 19 Open Access
Notes Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:144746 Serial 4658
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Author Sevik, C.; Wallbank, J.R.; Gulseren, O.; Peeters, F.M.; Çakir, D.
Title Gate induced monolayer behavior in twisted bilayer black phosphorus Type A1 Journal article
Year 2017 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 4 Issue 3 Pages 035025
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Optical and electronic properties of black phosphorus strongly depend on the number of layers and type of stacking. Using first-principles calculations within the framework of density functional theory, we investigate the electronic properties of bilayer black phosphorus with an interlayer twist angle of 90 degrees. These calculations are complemented with a simple (k) over right arrow . (p) over right arrow model which is able to capture most of the low energy features and is valid for arbitrary twist angles. The electronic spectrum of 90 degrees twisted bilayer black phosphorus is found to be x-y isotropic in contrast to the monolayer. However x-y anisotropy, and a partial return to monolayer-like behavior, particularly in the valence band, can be induced by an external out-of-plane electric field. Moreover, the preferred hole effective mass can be rotated by 90 degrees simply by changing the direction of the applied electric field. In particular, a +0.4 (-0.4) V angstrom(1) out-of-plane electric field results in a similar to 60% increase in the hole effective mass along the y (x) axis and enhances the m(y)*/m(x)* (m(x)*/m(y)*) ratio as much as by a factor of 40. Our DFT and (k) over right arrow . (p) over right arrow simulations clearly indicate that the twist angle in combination with an appropriate gate voltage is a novel way to tune the electronic and optical properties of bilayer phosphorus and it gives us a new degree of freedom to engineer the properties of black phosphorus based devices.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000406926600001 Publication Date 2017-08-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 13 Open Access
Notes ; This work was supported by the bilateral project between the The Scientific and Technological Research Council of Turkey (TUBITAK) and FWO-Flanders, Flemish Science Foundation (FWO-Vl) and the Methusalem foundation of the Flemish government. Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRGrid e-Infrastructure), and HPC infrastructure of the University of Antwerp (CalcUA) a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules foundation. We acknowledge the support from TUBITAK (Grant No. 115F024), ERC Synergy grant Hetero2D and the EU Graphene Flagship Project. We also thank Vladimir Fal'ko for helpful discussions. ; Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:145151 Serial 4717
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Author Moldovan, D.; Masir, M.R.; Peeters, F.M.
Title Magnetic field dependence of the atomic collapse state in graphene Type A1 Journal article
Year 2018 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 5 Issue 1 Pages 015017
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract <script type='text/javascript'>document.write(unpmarked('Quantum electrodynamics predicts that heavy atoms (Z \u003E Z(c) approximate to 170) will undergo the process of atomic collapse where electrons sink into the positron continuum and a new family of so-called collapsing states emerges. The relativistic electrons in graphene exhibit the same physics but at a much lower critical charge (Z(c) approximate to 1) which has made it possible to confirm this phenomenon experimentally. However, there exist conflicting predictions on the effect of a magnetic field on atomic collapse. These theoretical predictions are based on the continuum Dirac-Weyl equation, which does not have an exact analytical solution for the interplay of a supercritical Coulomb potential and the magnetic field. Approximative solutions have been proposed, but because the two effects compete on similar energy scales, the theoretical treatment varies depending on the regime which is being considered. These limitations are overcome here by starting from a tight-binding approach and computing exact numerical results. By avoiding special limit cases, we found a smooth evolution between the different regimes. We predict that the atomic collapse effect persists even after the magnetic field is activated and that the critical charge remains unchanged. We show that the atomic collapse regime is characterized: (1) by a series of Landau level anticrossings and (2) by the absence of root B scaling of the Landau levels with regard to magnetic field strength.'));
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000415015000001 Publication Date 2017-10-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 13 Open Access
Notes ; We thank Eva Andrei, Jinhai Mao and Yuhang Jiang for insightful discussions. This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem Funding of the Flemish Government. ; Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:147361UA @ admin @ c:irua:147361 Serial 4884
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Author Peymanirad, F.; Singh, S.K.; Ghorbanfekr-Kalashami, H.; Novoselov, K.S.; Peeters, F.M.; Neek-Amal, M.
Title Thermal activated rotation of graphene flake on graphene Type A1 Journal article
Year 2017 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 4 Issue 2 Pages 025015
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The self rotation of a graphene flake over graphite is controlled by the size, initial misalignment and temperature. Using both ab initio calculations and molecular dynamics simulations, we investigate annealing effects on the self rotation of a graphene flake on a graphene substrate. The energy barriers for rotation and drift of a graphene flake over graphene is found to be smaller than 25 meV/atom which is comparable to thermal energy. We found that small flakes (of about similar to 4 nm) are more sensitive to temperature and initial misorientation angles than larger one (beyond 10 nm). The initial stacking configuration of the flake is found to be important for its dynamics and time evolution of misalignment. Large flakes, which are initially in the AA-or AB-stacking state with small misorientation angle, rotate and end up in the AB-stacking configuration. However small flakes can they stay in an incommensurate state specially when the initial misorientation angle is larger than 2 degrees. Our results are in agreement with recent experiments.
Address
Corporate Author Thesis
Publisher IOP Publishing Place of Publication Bristol Editor
Language Wos 000424399600005 Publication Date 2017-02-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 16 Open Access
Notes ; We would like to acknowledge Annalisa Fasolino and MM van Wijk for providing us with the implemented parameters of REBO-KC [5] in LAMMPS. This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem foundation. ; Approved Most recent IF: 6.937
Call Number UA @ lucian @ c:irua:149364 Serial 4984
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Author Tiwari, S.; Van de Put, M.L.; Sorée, B.; Vandenberghe, W.G.
Title Carrier transport in two-dimensional topological insulator nanoribbons in the presence of vacancy defects Type A1 Journal article
Year 2019 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 6 Issue 2 Pages 025011
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using the non-equilibrium Green's function formalism, we study carrier transport through imperfect two-dimensional (2D) topological insulator (TI) ribbons. In particular, we investigate the effect of vacancy defects on the carrier transport in 2D TI ribbons with hexagonal lattice structure. To account for the random distribution of the vacancy defects, we present a statistical study of varying defect densities by stochastically sampling different defect configurations. We demonstrate that the topological edge states of TI ribbons are fairly robust against a high concentration (up to 2%) of defects. At very high defect densities, we observe an increased inter-edge interaction, mediated by the localisation of the edge states within the bulk region. This effect causes significant back-scattering of the, otherwise protected, edge-states at very high defect concentrations (>2%), resulting in a loss of conduction through the TI ribbon. We discuss how this coherent vacancy scattering can be used to our advantage for the development of TI-based transistors. We find that there is an optimal concentration of vacancies yielding an ON-OFF current ratio of up to two orders of magnitude. Finally, we investigate the importance of spin-orbit coupling on the robustness of the edge states in the TI ribbon and show that increased spin-orbit coupling could further increase the ON-OFF ratio.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000457856400002 Publication Date 2019-01-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 3 Open Access
Notes ; This material is based in part upon work supported by the National Science Foundation under Grant Number 1710066. The project or effort depicted was or is sponsored by the Department of Defense, Defense Threat Reduction Agency. The content of the information does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred. This work was supported by imec's Industrial Affiliation Program. ; Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:157464 Serial 5198
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Author Li, L.L.; Partoens, B.; Xu, W.; Peeters, F.M.
Title Electric-field modulation of linear dichroism and Faraday rotation in few-layer phosphorene Type A1 Journal article
Year 2019 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 6 Issue 1 Pages 015032
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Electro-optical modulators, which use an electric voltage (or an electric field) to modulate a beam of light, are essential elements in present-day telecommunication devices. Using a self-consistent tight-binding approach combined with the standard Kubo formula, we show that the optical conductivity and the linear dichroism of few-layer phosphorene can be modulated by a perpendicular electric field. We find that the field-induced charge screening plays a significant role in modulating the optical conductivity and the linear dichroism. Distinct absorption peaks are induced in the conductivity spectrum due to the strong quantum confinement along the out-of-plane direction and to the field-induced forbidden-to-allowed transitions. The field modulation of the linear dichroism becomes more pronounced with increasing number of phosphorene layers. We also show that the Faraday rotation is present in few-layer phosphorene even in the absence of an external magnetic field. This optical Hall effect is induced by the reduced lattice symmetry of few-layer phosphorene. The Faraday rotation is greatly influenced by the field-induced charge screening and is strongly dependent on the strength of perpendicular electric field and on the number of phosphorene layers.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000454321100002 Publication Date 2018-11-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 19 Open Access
Notes ; This work was financially supported by the Flemish Science Foundation (FWO-Vl) and by the FLAG-ERA project TRANS-2D-TMD. ; Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:156776 Serial 5207
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Author Heyne, M.H.; Marinov, D.; Braithwaite, N.; Goodyear, A.; de Marneffe, J.-F.; Cooke, M.; Radu, I.; Neyts, E.C.; De Gendt, S.
Title A route towards the fabrication of 2D heterostructures using atomic layer etching combined with selective conversion Type A1 Journal article
Year 2019 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 6 Issue 3 Pages 035030
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract Heterostructures of low-dimensional semiconducting materials, such as transition metal dichalcogenides (MX2), are promising building blocks for future electronic and optoelectronic devices. The patterning of one MX2 material on top of another one is challenging due to their structural similarity. This prevents an intrinsic etch stop when conventional anisotropic dry etching processes are used. An alternative approach consist in a two-step process, where a sacrificial silicon layer is pre-patterned with a low damage plasma process, stopping on the underlying MoS2 film. The pre-patterned layer is used as sacrificial template for the formation of the top WS2 film. This study describes the optimization of a cyclic Ar/Cl-2 atomic layer etch process applied to etch silicon on top of MoS2, with minimal damage, followed by a selective conversion of the patterned Si into WS2. The impact of the Si atomic layer etch towards the MoS2 is evaluated: in the ion energy range used for this study, MoS2 removal occurs in the over-etch step over 1-2 layers, leading to the appearance of MoOx but without significant lattice distortions to the remaining layers. The combination of Si atomic layer etch, on top of MoS2, and subsequent Si-to-WS2 selective conversion, allows to create a WS2/MoS2 heterostructure, with clear Raman signals and horizontal lattice alignment. These results demonstrate a scalable, transfer free method to achieve horizontally individually patterned heterostacks and open the route towards wafer-level processing of 2D materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000468335500004 Publication Date 2019-04-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:160229 Serial 5266
Permanent link to this record
 
 
Author Van Pottelberge, R.; Moldovan, D.; Milovanović, S.P.; Peeters, F.M.
Title Molecular collapse in monolayer graphene Type A1 Journal article
Year 2019 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 6 Issue 4 Pages 045047
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Atomic collapse is a phenomenon inherent to relativistic quantum mechanics where electron states dive in the positron continuum for highly charged nuclei. This phenomenon was recently observed in graphene. Here we investigate a novel collapse phenomenon when multiple sub- and supercritical charges of equal strength are put close together as in a molecule. We construct a phase diagram which consists of three distinct regions: (1) subcritical, (2) frustrated atomic collapse, and (3) molecular collapse. We show that the single impurity atomic collapse resonances rearrange themselves to form molecular collapse resonances which exhibit a distinct bonding, anti-bonding and non-bonding character. Here we limit ourselves to systems consisting of two and three charges. We show that by tuning the distance between the charges and their strength a high degree of control over the molecular collapse resonances can be achieved.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000487692200003 Publication Date 2019-08-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 6 Open Access
Notes ; We thank Matthias Van der Donck for fruitful discussions. This work was supported by the Research Foundation of Flanders (FWO-V1) through an aspirant research Grant for RVP and a postdoctoral Grant for SPM. ; Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:163756 Serial 5422
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Author Bacaksiz, C.; Yagmurcukardes, M.; Peeters, F.M.; Milošević, M.V.
Title Hematite at its thinnest limit Type A1 Journal article
Year 2020 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume 7 Issue 2 Pages 025029
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Motivated by the recent synthesis of two-dimensional alpha-Fe2O3 (Balan et al 2018 Nat. Nanotechnol. 13 602), we analyze the structural, vibrational, electronic and magnetic properties of single- and few-layer alpha-Fe2O3 compared to bulk, by ab initio and Monte-Carlo simulations. We reveal how monolayer alpha-Fe2O3 (hematene) can be distinguished from the few-layer structures, and how they all differ from bulk through observable Raman spectra. The optical spectra exhibit gradual shift of the prominent peak to higher energy, as well as additional features at lower energy when alpha-Fe2O3 is thinned down to a monolayer. Both optical and electronic properties have strong spin asymmetry, meaning that lower-energy optical and electronic activities are allowed for the single-spin state. Finally, our considerations of magnetic properties reveal that 2D hematite has anti-ferromagnetic ground state for all thicknesses, but the critical temperature for Morin transition increases with decreasing sample thickness. On all accounts, the link to available experimental data is made, and further measurements are prompted.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000537341000002 Publication Date 2020-01-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.5 Times cited 11 Open Access
Notes ; This work was supported by Research Foundation-Flanders (FWO-Vlaanderen). Computational resources were provided by Flemish Supercomputer Center(VSC), and TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). Part of this work was also supported by FLAG-ERA project TRANS-2D-TMD and TOPBOF-UAntwerp. MY was supported by a postdoctoral fellowship from the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 5.5; 2020 IF: 6.937
Call Number UA @ admin @ c:irua:170301 Serial 6533
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Author Reyntjens, P.D.; Tiwari, S.; van de Put, M.L.; Sorée, B.; Vandenberghe, W.G.
Title Magnetic properties and critical behavior of magnetically intercalated WSe₂ : a theoretical study Type A1 Journal article
Year 2021 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume 8 Issue 2 Pages 025009
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Transition metal dichalcogenides, intercalated with transition metals, are studied for their potential applications as dilute magnetic semiconductors. We investigate the magnetic properties of WSe2 doped with third-row transition metals (Co, Cr, Fe, Mn, Ti and V). Using density functional theory in combination with Monte Carlo simulations, we obtain an estimate of the Curie or Neel temperature. We find that the magnetic ordering is highly dependent on the dopant type. While Ti and Cr-doped WSe2 have a ferromagnetic ground state, V, Mn, Fe and Co-doped WSe2 are antiferromagnetic in their ground state. For Fe doped WSe2, we find a high Curie-temperature of 327 K. In the case of V-doped WSe2, we find that there are two distinct magnetic phase transitions, originating from a frustrated in-plane antiferromagnetic exchange interaction and a ferromagnetic out-of-plane interaction. We calculate the formation energy and reveal that, in contrast to earlier reports, the formation energy is positive for the intercalated systems studied here. We also show that in the presence of W-vacancies, it becomes favorable for Ti, Fe, and Co to intercalate in WSe2.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000601127600001 Publication Date 2020-12-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 1 Open Access OpenAccess
Notes ; The project or effort depicted was or is sponsored by the Department of Defense, Defense Threat Reduction Agency. The content of the information does not necessarily reflect the position or the policy of the federal government, and no official endorsement should be inferred. This material is based upon work supported by the National Science Foundation under Grant No. 1802166. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work was supported by IMEC's Industrial Affiliation Program. Peter D Reyntjens acknowledges support by the Eugene McDermott Fellowship program, under Grant Number 201806. ; Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:174951 Serial 6692
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Author Lavor, I.R.; Cavalcante, L.S.R.; Chaves, A.; Peeters, F.M.; Van Duppen, B.
Title Probing the structure and composition of van der Waals heterostructures using the nonlocality of Dirac plasmons in the terahertz regime Type A1 Journal article
Year 2021 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume 8 Issue 1 Pages 015014
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Dirac plasmons in graphene are very sensitive to the dielectric properties of the environment. We show that this can be used to probe the structure and composition of van der Waals heterostructures (vdWh) put underneath a single graphene layer. In order to do so, we assess vdWh composed of hexagonal boron nitride and different types of transition metal dichalcogenides (TMDs). By performing realistic simulations that account for the contribution of each layer of the vdWh separately and including the importance of the substrate phonons, we show that one can achieve single-layer resolution by investigating the nonlocal nature of the Dirac plasmon-polaritons. The composition of the vdWh stack can be inferred from the plasmon-phonon coupling once it is composed by more than two TMD layers. Furthermore, we show that the bulk character of TMD stacks for plasmonic screening properties in the terahertz regime is reached only beyond 100 layers.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000582820500001 Publication Date 2020-10-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 2 Open Access OpenAccess
Notes ; This work was financially supported by the Brazilian Council for Research (CNPq), Brazilian National Council for the Improvement of Higher Education (CAPES) and by the Research Foundation Flanders (FWO) through a postdoctoral fellowship to B.V.D. ; Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:173507 Serial 6696
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Author Chen, L.; Elibol, K.; Cai, H.; Jiang, C.; Shi, W.; Chen, C.; Wang, H.S.; Wang, X.; Mu, X.; Li, C.; Watanabe, K.; Taniguchi, T.; Guo, Y.; Meyer, J.C.; Wang, H.
Title Direct observation of layer-stacking and oriented wrinkles in multilayer hexagonal boron nitride Type A1 Journal article
Year 2021 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume 8 Issue 2 Pages 024001
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Hexagonal boron nitride (h-BN) has long been recognized as an ideal substrate for electronic devices due to its dangling-bond-free surface, insulating nature and thermal/chemical stability. These properties of the h-BN multilayer are mainly determined by its lattice structure. Therefore, to analyse the lattice structure and orientation of h-BN crystals becomes important. Here, the stacking order and wrinkles of h-BN are investigated by transmission electron microscopy. It is experimentally confirmed that the layers in the h-BN flakes are arranged in the AA ' stacking. The wrinkles in a form of threefold network throughout the h-BN crystal are oriented along the armchair direction, and their formation mechanism was further explored by molecular dynamics simulations. Our findings provide a deep insight about the microstructure of h-BN and shed light on the structural design/electronic modulations of two-dimensional crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000605937500001 Publication Date 2020-12-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited Open Access OpenAccess
Notes Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:174950 Serial 6723
Permanent link to this record
 
 
Author Pandey, T.; Peeters, F.M.; Milošević, M.V.
Title Pivotal role of magnetic ordering and strain in lattice thermal conductivity of chromium-trihalide monolayers Type A1 Journal article
Year 2022 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 9 Issue 1 Pages 015034
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Understanding the coupling between spin and phonons is critical for controlling the lattice thermal conductivity (kappa ( l )) in magnetic materials, as we demonstrate here for CrX3 (X = Br and I) monolayers. We show that these compounds exhibit large spin-phonon coupling (SPC), dominated by out-of-plane vibrations of Cr atoms, resulting in significantly different phonon dispersions in ferromagnetic (FM) and paramagnetic (PM) phases. Lattice thermal conductivity calculations provide additional evidence for strong SPC, where particularly large kappa ( l ) is found for the FM phase. Most strikingly, PM and FM phases exhibit radically different behavior with tensile strain, where kappa ( l ) increases with strain for the PM phase, and strongly decreases for the FM phase-as we explain through analysis of phonon lifetimes and scattering rates. Taken all together, we uncover the high significance of SPC on the phonon transport in CrX3 monolayers, a result extendable to other 2D magnetic materials, that will be useful in further design of thermal spin devices.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000735170300001 Publication Date 2021-12-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.5 Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: 5.5
Call Number UA @ admin @ c:irua:184642 Serial 7010
Permanent link to this record
 
 
Author Petrov, M.; Bekaert, J.; Milošević, M.V.
Title Superconductivity in gallenene Type A1 Journal article
Year 2021 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume 8 Issue 3 Pages 035056
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Among the large variety of two-dimensional (2D) materials discovered to date, elemental monolayers that host superconductivity are very rare. Using ab initio calculations we show that recently synthesized gallium monolayers, coined gallenene, are intrinsically superconducting through electron-phonon coupling. We reveal that Ga-100 gallenene, a planar monolayer isostructural with graphene, is the structurally simplest 2D superconductor to date, furthermore hosting topological edge states due to its honeycomb structure. Our anisotropic Eliashberg calculations show distinctly three-gap superconductivity in Ga-100, in contrast to the alternative buckled Ga-010 gallenene which presents a single anisotropic superconducting gap. Strikingly, the critical temperature (T ( c )) of gallenene is in the range of 7-10 K, exceeding the T ( c ) of bulk gallium from which it is exfoliated. Finally we explore chemical functionalization of gallenene with hydrogen, and report induced multigap superconductivity with an enhanced T ( c ) in the resulting gallenane compound.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000667458500001 Publication Date 2021-06-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.937 Times cited 8 Open Access OpenAccess
Notes Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:179623 Serial 7025
Permanent link to this record
 
 
Author Lavor, I.R.; Chaves, A.; Peeters, F.M.; Van Duppen, B.
Title Tunable coupling of terahertz Dirac plasmons and phonons in transition metal dichalcogenide-based van der Waals heterostructures Type A1 Journal article
Year 2021 Publication 2d Materials Abbreviated Journal (up) 2D Mater
Volume Issue Pages 015018
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons' properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene's Fermi energy and changing TMD layer number.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000722020100001 Publication Date 2021-11-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record
Impact Factor 6.937 Times cited Open Access OpenAccess
Notes Approved Most recent IF: 6.937
Call Number UA @ admin @ c:irua:183053 Serial 7036
Permanent link to this record
 
 
Author Chaves, A.; Covaci, L.; Peeters, F.M.; Milošević, M.V.
Title Topologically protected moiré exciton at a twist-boundary in a van der Waals heterostructure Type A1 Journal article
Year 2022 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 9 Issue 2 Pages 025012
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract A twin boundary in one of the layers of a twisted van der Waals heterostructure separates regions with near opposite inter-layer twist angles. In a MoS<sub>2</sub>/WSe<sub>2</sub>bilayer, the regions with<inline-formula><tex-math><?CDATA $Rh^h$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>h</mi></msubsup></math><inline-graphic href=“tdmac529dieqn1.gif” type=“simple” /></inline-formula>and<inline-formula><tex-math><?CDATA $Rh^X$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>X</mi></msubsup></math><inline-graphic href=“tdmac529dieqn2.gif” type=“simple” /></inline-formula>stacking registry that defined the sub-lattices of the moiré honeycomb pattern would be mirror-reflected across such a twist boundary. In that case, we demonstrate that topologically protected chiral moiré exciton states are confined at the twist boundary. These are one-dimensional and uni-directional excitons with opposite velocities for excitons composed by electronic states with opposite valley/spin character, enabling intrinsic, guided, and far reaching valley-polarized exciton currents.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000760518100001 Publication Date 2022-04-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.5 Times cited Open Access OpenAccess
Notes Fonds Wetenschappelijk Onderzoek; Conselho Nacional de Desenvolvimento Científico e Tecnológico, PQ ; Approved Most recent IF: 5.5
Call Number CMT @ cmt @c:irua:187124 Serial 7046
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Author Menezes, R.M.; Šabani, D.; Bacaksiz, C.; de Souza Silva, C.C.; Milošević, M.V.
Title Tailoring high-frequency magnonics in monolayer chromium trihalides Type A1 Journal article
Year 2022 Publication 2D materials Abbreviated Journal (up) 2D Mater
Volume 9 Issue 2 Pages 025021
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Monolayer chromium-trihalides, the archetypal two-dimensional (2D) magnetic materials, are readily suggested as a promising platform for high-frequency magnonics. Here we detail the spin-wave properties of monolayer CrBr<sub>3</sub>and CrI<sub>3</sub>, using spin-dynamics simulations parametrized from the first principles. We reveal that spin-wave dispersion can be tuned in a broad range of frequencies by strain, paving the way towards flexo-magnonic applications. We further show that ever-present halide vacancies in these monolayers host sufficiently strong Dzyaloshinskii-Moriya interaction to scatter spin-waves, which promotes design of spin-wave guides by defect engineering. Finally we discuss the spectra of spin-waves propagating across a moiré-periodic modulation of magnetic parameters in a van der Waals heterobilayer, and show that the nanoscale moiré periodicities in such samples are ideal for realization of a magnonic crystal in the terahertz frequency range. Recalling the additional tunability of magnetic 2D materials by electronic gating, our results situate these systems among the front-runners for prospective high-frequency magnonic applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000771735500001 Publication Date 2022-04-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2053-1583 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.5 Times cited Open Access OpenAccess
Notes Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco; Special Research Funds of the University of Antwerp; Conselho Nacional de Desenvolvimento Científico e Tecnológico; Fonds Wetenschappelijk Onderzoek; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; Approved Most recent IF: 5.5
Call Number CMT @ cmt @c:irua:187125 Serial 7048
Permanent link to this record
 
 
Author Raveau, B.; Michel, C.; Hervieu, M.; Van Tendeloo, G.; Maignan, A.
Title Stabilization of mercury-based superconductors by foreign cations Type A1 Journal article
Year 1994 Publication Annales de chimie (1914) T2 – 4th North-African Materials Science Symposium (JMSM 94), NOV 23-24, 1994, CASABLANCA, MOROCCO Abbreviated Journal (up) 4th North-African Materials Science Symposium (JMSM 94), NOV 23-24, 1994, CASABLANCA, MOROCCO
Volume 19 Issue 7-8 Pages 487-492
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The recently discovered superconducting mercury-based cuprates HgBa2Can-1CunO2n+2+delta have proved difficult to synthesize as single phases and are sensitive to environment (CO2, moisture). The present paper gives an overview of new series mercury based superconductors, whose stabilisation is based on the fact that a foreign cation with a higher valency than Hg(II) must be introduced in the mercury layers, in order to fill up partially the oxygen vacancies of these layers. By this method, several new series of superconductors involving strontium instead of barium with critical temperatures ranging from 27 K to 95 K have been isolated : Hg0.5Bi0.5Sr2-xLaxCuO4+delta, Hg(0.5)Bi(0.5)Sr(2)Ca(1-x)R(x)Cu(2)O(6+delta) (R Y, Nd, Pr), Pb0.7Hg0.3Sr2-xLaxCuO4+delta, Pb(0.7)Hg(0.3)Sr(2)Ca(1-x)R(x)Cu(2)O(6+delta) (R = Y, Nd) Hg(1-x)Pr(x)Sr(2)A(1-x')Pr(x') Cu2O6+delta (A = Sr, Ca), Pb0.7Hg0.3Sr2Cu2CO3O7 and Hg1-xCrxSr2CuO4+delta. The behaviour of the praseodymium cuprates that exhibit a rather sharp transition and reach a Tc of 85 K is especially discussed. A method to synthesize new ''Ba-Hg'' superconducting cuprates with the 1212 structure at normal pressure with a Tc up to 110 K is also presented.
Address
Corporate Author Thesis
Publisher Place of Publication Paris Editor
Language Wos A1994RC75300027 Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0151-9107 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited 2 Open Access
Notes Approved PHYSICS, APPLIED 28/145 Q1 #
Call Number UA @ lucian @ c:irua:104472 Serial 3137
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Author Janssens, K.; Vincze, L.; Vekemans, B.; Aerts, A.; Adams, F.; Jones, K.W.; Knöchel, A.
Title Synchrotron radiation induced X-ray microfluorescence analysis Type A1 Journal article
Year 1996 Publication Microchimica acta T2 – 4th Workshop of the European-Microanalysis-Society on Modern, Developments and Applications in Microbeam Analysis, MAY, 1995, ST MALO, FRANCE Abbreviated Journal (up) 4th Workshop of the European-Microanalysis-Society on Modern, Developments and Applications in Micro
Volume Issue s:[13] Pages 87-115
Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Abstract mu-XRF is the microscopic equivalent of the well-established multielement analytical technique. In this paper, after comparing the interaction of X-ray photons, electrons and protons with matter and an introduction to synchrotron rings and microfocussing of X-rays, the instrumentation for mu-XRF is discussed, both for laboratory source and synchrotron based setups and the analytical characteristics of mu-XRF are contrasted to that of other microanalytical techniques, Also, this issue of quantification of mu-XRF data is addressed; the applicability of the method in archeological and geological analysis is illustrated.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos A1996VT82300006 Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:104410 Serial 5866
Permanent link to this record
 
 
Author Janssens, K.; Vekemans, B.; Adams, F.; van Espen, P.; Mutsaers, P.
Title Accurate evaluation of \mu-PIXE and \mu-XRF spectral data through iterative least squares fitting Type A1 Journal article
Year 1996 Publication Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms T2 – 7th International Conference on Particle Induced X-ray Emission and Its Analytical Applications, MAY 26-30, 1995, Abano Terme, Italy Abbreviated Journal (up) 7th International Conference on Particle Induced X-ray Emission and Its Analytical Applications, MAY
Volume 109 Issue Pages 179-185
Keywords A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Chemometrics (Mitac 3)
Abstract The integration of the nonlinear least squares X-ray spectrum evaluation progam AXIL. into a mu-PIXE and a mu-XRF setup is discussed. The use of the software when procesing data sets derived from biological and geological samples is described.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos A1996UV44400035 Publication Date 2002-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0168-583x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:95887 Serial 5457
Permanent link to this record
 
 
Author Khalilov, U.; Bogaerts, A.; Neyts, E.C.
Title Toward the Understanding of Selective Si Nano-Oxidation by Atomic Scale Simulations Type A1 Journal article
Year 2017 Publication Accounts of chemical research Abbreviated Journal (up) Accounts Chem Res
Volume 50 Issue 50 Pages 796-804
Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Abstract The continuous miniaturization of nanodevices, such as transistors, solar cells, and optical fibers, requires the controlled synthesis of (ultra)thin gate oxides (<10 nm), including Si gate-oxide (SiO2) with high quality at the atomic scale. Traditional thermal growth of SiO2 on planar Si surfaces, however, does not allow one to obtain such ultrathin oxide due to either the high oxygen diffusivity at high temperature or the very low sticking ability of incident oxygen at low temperature. Two recent techniques, both operative at low (room) temperature, have been put forward to overcome these obstacles: (i) hyperthermal oxidation of planar Si surfaces and (ii) thermal or plasma-assisted oxidation of nonplanar Si surfaces, including Si nanowires (SiNWs). These nanooxidation processes are, however, often difficult to study experimentally, due to the key intermediate processes taking place on the nanosecond time scale.

In this Account, these Si nano-oxidation techniques are discussed from a computational point of view and compared to both hyperthermal and thermal oxidation experiments, as well as to well-known models of thermal oxidation, including the Deal−Grove, Cabrera−Mott, and Kao models and several alternative mechanisms. In our studies, we use reactive molecular dynamics (MD) and hybrid MD/Monte Carlo simulation techniques, applying the Reax force field. The incident energy of oxygen species is chosen in the range of 1−5 eV in hyperthermal oxidation of planar Si surfaces in order to prevent energy-induced damage. It turns out that hyperthermal growth allows for two growth modes, where the ultrathin oxide thickness depends on either (1) only the kinetic energy of the incident oxygen species at a growth temperature below Ttrans = 600 K, or (2) both the incident energy and the growth temperature at a growth temperature above Ttrans. These modes are specific to such ultrathin oxides, and are not observed in traditional thermal oxidation, nor theoretically considered by already existing models. In the case of thermal or plasma-assisted oxidation of small Si nanowires, on the other hand, the thickness of the ultrathin oxide is a function of the growth temperature and the nanowire diameter. Below Ttrans, which varies with the nanowire diameter, partially oxidized SiNW are formed, whereas complete oxidation to a SiO2 nanowire occurs only above Ttrans. In both nano-oxidation processes at lower temperature (T < Ttrans), final sandwich c-Si|SiOx|a-SiO2 structures are obtained due to a competition between overcoming the energy barrier to penetrate into Si subsurface layers and the compressive stress (∼2−3 GPa) at the Si crystal/oxide interface. The overall atomic-simulation results strongly indicate that the thickness of the intermediate SiOx (x < 2) region is very limited (∼0.5 nm) and constant irrespective of oxidation parameters. Thus, control over the ultrathin SiO2 thickness with good quality is indeed possible by accurately tuning the oxidant energy, oxidation temperature and surface curvature.

In general, we discuss and put in perspective these two oxidation mechanisms for obtaining controllable ultrathin gate-oxide films, offering a new route toward the fabrication of nanodevices via selective nano-oxidation.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000399859800016 Publication Date 2017-04-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0001-4842 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 20.268 Times cited 5 Open Access OpenAccess
Notes Fonds Wetenschappelijk Onderzoek, 12M1315N ; Approved Most recent IF: 20.268
Call Number PLASMANT @ plasmant @ c:irua:142638 Serial 4561
Permanent link to this record
 
 
Author Janssens, K.; Dik, J.; Cotte, M.; Susini, J.
Title Photon-based techniques for nondestructive subsurface analysis of painted cultural heritage artifacts Type A1 Journal article
Year 2010 Publication Accounts of chemical research Abbreviated Journal (up) Accounts Chem Res
Volume 43 Issue 6 Pages 814-825
Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Abstract Often, just micrometers below a paintings surface lies a wealth of information, both with Old Masters such as Peter Paul Rubens and Rembrandt van Rijn and with more recent artists of great renown such as Vincent Van Gogh and James Ensor. Subsurface layers may include underdrawing, underpainting, and alterations, and in a growing number of cases conservators have discovered abandoned compositions on paintings, illustrating artists practice of reusing a canvas or panel. The standard methods for studying the inner structure of cultural heritage (CH) artifacts are infrared reflectography and X-ray radiography, techniques that are optionally complemented with the microscopic analysis of cross-sectioned samples. These methods have limitations, but recently, a number of fundamentally new approaches for fully imaging the buildup of hidden paint layers and other complex three-dimensional (3D) substructures have been put into practice. In this Account, we discuss these developments and their recent practical application with CH artifacts. We begin with a tabular summary of 14 IR- and X-ray-based imaging methods and then continue with a discussion of each technique, illustrating CH applications with specific case studies. X-ray-based tomographic and laminographic techniques can be used to generate 3D renditions of artifacts of varying dimensions. These methods are proving invaluable for exploring inner structures, identifying the conservation state, and postulating the original manufacturing technology of metallic and other sculptures. In the analysis of paint layers, terahertz time-domain spectroscopy (THz-TDS) can highlight interfaces between layers in a stratigraphic buildup, whereas macrosopic scanning X-ray fluorescence (MA-XRF) has been employed to measure the distribution of pigments within these layers. This combination of innovative methods provides topographic and color information about the micrometer depth scale, allowing us to look into paintings in an entirely new manner. Over the past five years, several new variants of traditional IR- and X-ray-based imaging methods have been implemented by conservators and museums, and the first reports have begun to emerge in the primary research literature. Applying these state-of-the-art techniques in a complementary fashion affords a more comprehensive view of paintings and other artworks.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000278842500013 Publication Date 2010-05-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0001-4842 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 20.268 Times cited 78 Open Access
Notes ; This research was supported by the Interuniversity Attraction Poles Programme-Belgian Science Policy (IUAP VI/16). The text also presents results of FWO (Brussels, Belgium) projects nr. G.0704.08 and G.0179.09 and from the UA-BOF GOA programme. ; Approved Most recent IF: 20.268; 2010 IF: 21.852
Call Number UA @ admin @ c:irua:83983 Serial 5772
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Author Cotte, M.; Susini, J.; Dik, J.; Janssens, K.
Title Synchrotron-based X-ray absorption spectroscopy for art conservation: looking back and looking forward Type A1 Journal article
Year 2010 Publication Accounts of chemical research Abbreviated Journal (up) Accounts Chem Res
Volume 43 Issue 6 Pages 705-714
Keywords A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Abstract A variety of analytical techniques augmented by the use of synchrotron radiation (SR), such as X-ray fluorescence (SR-XRF) and X-ray diffraction (SR-XRD), are now readily available, and they differ little, conceptually, from their common laboratory counterparts. Because of numerous advantages afforded by SR-based techniques over benchtop versions, however, SR methods have become popular with archaeologists, art historians, curators, and other researchers in the field of cultural heritage (CH). Although the CH community now commonly uses both SR-XRF and SR-XRD, the use of synchrotron-based X-ray absorption spectroscopy (SR-XAS) techniques remains marginal, mostly because CH specialists rarely interact with SR physicists. In this Account, we examine the basic principles and capabilities of XAS techniques in art preservation. XAS techniques offer a combination of features particularly well-suited for the chemical analysis of works of art. The methods are noninvasive, have low detection limits, afford high lateral resolution, and provide exceptional chemical sensitivity. These characteristics are highly desirable for the chemical characterization of precious, heterogeneous, and complex materials. In particular, the chemical mapping capability, with high spatial resolution that provides information about local composition and chemical states, even for trace elements, is a unique asset. The chemistry involved in both the objects history (that is, during fabrication) and future (that is, during preservation and restoration treatments) can be addressed by XAS. On the one hand, many studies seek to explain optical effects occurring in historical glasses or ceramics by probing the molecular environment of relevant chromophores. Hence, XAS can provide insight into craft skills that were mastered years, decades, or centuries ago but were lost over the course of time. On the other hand, XAS can also be used to characterize unwanted reactions, which are then considered alteration phenomena and can dramatically alter the objects original visual properties. In such cases, the bulk elemental composition is usually unchanged. Hence, monitoring oxidation state (or, more generally, other chemical modifications) can be of great importance. Recent applications of XAS in art conservation are reviewed and new trends are discussed, highlighting the value (and future possibilities) of XAS, which remains, given its potential, underutilized in the CH community.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000278842500003 Publication Date 2010-01-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0001-4842 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 20.268 Times cited 74 Open Access
Notes ; ; Approved Most recent IF: 20.268; 2010 IF: 21.852
Call Number UA @ admin @ c:irua:83982 Serial 5861
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