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Author Liao, Z.; Gauquelin, N.; Green, R.J.; Müller-Caspary, K.; Lobato, I.; Li, L.; Van Aert, S.; Verbeeck, J.; Huijben, M.; Grisolia, M.N.; Rouco, V.; El Hage, R.; Villegas, J.E.; Mercy, A.; Bibes, M.; Ghosez, P.; Sawatzky, G.A.; Rijnders, G.; Koster, G. pdf  url
doi  openurl
  Title Metal–insulator-transition engineering by modulation tilt-control in perovskite nickelates for room temperature optical switching Type A1 Journal article
  Year (down) 2018 Publication America Abbreviated Journal P Natl Acad Sci Usa  
  Volume 115 Issue 38 Pages 9515-9520  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract In transition metal perovskites ABO3 the physical properties are largely driven by the rotations of the BO6 octahedra, which can be tuned in thin films through strain and dimensionality control. However, both approaches have fundamental and practical limitations due to discrete and indirect variations in bond angles, bond lengths and film symmetry by using commercially available substrates. Here, we introduce modulation tilt control as a new approach to tune the ground state of perovskite oxide thin films by acting explicitly on the oxygen octahedra rotation modes, i.e. directly on the bond angles. By intercalating the prototype SmNiO3 target material with a tilt-control layer, we cause the system to change the natural amplitude of a given rotation mode without affecting the interactions. In contrast to strain and dimensionality engineering, our method enables a continuous fine-tuning of the materials properties. This is achieved through two independent adjustable parameters: the nature of the tilt-control material (through its symmetry, elastic constants and oxygen rotation angles) and the relative thicknesses of the target and tilt-control materials. As a result, a magnetic and electronic phase diagram can be obtained, normally only accessible by A-site element substitution, within the single SmNiO3 compound. With this unique approach, we successfully adjusted the metal-insulator transition (MIT) to room temperature to fulfill the desired conditions for optical switching applications.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000447224900057 Publication Date 2018-09-05  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0027-8424 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 9.661 Times cited 50 Open Access OpenAccess  
  Notes We would like to acknowledge Prof. Z. Zhong for stimulated discussion. M.H., G.K. and G.R. acknowledge funding from DESCO program of the Dutch Foundation for Fundamental Research on Matter (FOM) with financial support from the Netherlands Organization for Scientific Research (NWO). This work was funded by the European Union Council under the 7th Framework Program (FP7) grant nr NMP3-LA-2010-246102 IFOX. J.V., S.V.A, N.G. and K.M.C. acknowledge funding from FWO projects G.0044.13N, G.0374.13N, G. 0368.15N, and G.0369.15N. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. N.G. acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant 278510 VORTEX. N.G. and J.V. acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483- ESTEEM2). The Canadian work was supported by NSERC and the Max Planck-UBC Centre for Quantum Materials. Some experiments for this work were performed at the Canadian Light Source, which is funded by the Canada Foundation for Innovation, NSERC, the National Research Council of Canada, the Canadian Institutes of Health Research, the Government of Saskatchewan, Western Economic Diversification Canada, and the University of Saskatchewan. MB acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC CoG grant MINT #615759. A.M. and Ph.G. were supported by the ARC project AIMED and F.R.S-FNRS PDR project HiT4FiT and acknowledge access to Céci computing facilities funded by F.R.S-FNRS (Grant No 2.5020.1), Tier-1 supercomputer of the Fédération Wallonie-Bruxelles funded by the Walloon Region (Grant No 1117545) and HPC resources from the PRACE project Megapasta. Approved Most recent IF: 9.661  
  Call Number EMAT @ emat @c:irua:154784UA @ admin @ c:irua:154784 Serial 5059  
Permanent link to this record
 

 
Author Song, H.-D.; Wu, Y.-F.; Yang, X.; Ren, Z.; Ke, X.; Kurttepeli, M.; Tendeloo, G.V.; Liu, D.; Wu, H.-C.; Yan, B.; Wu, X.; Duan, C.-G.; Han, G.; Liao, Z.-M.; Yu, D. pdf  doi
openurl 
  Title Asymmetric Modulation on Exchange Field in a Graphene/BiFeO3Heterostructure by External Magnetic Field Type A1 Journal article
  Year (down) 2018 Publication Nano letters Abbreviated Journal Nano Lett  
  Volume 18 Issue 4 Pages 2435-2441  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Graphene, having all atoms on its surface, is favorable to extend the functions by introducing the spin–orbit coupling and magnetism through proximity effect. Here, we report the tunable interfacial exchange field produced by proximity coupling in graphene/BiFeO3 heterostructures. The exchange field has a notable dependence with external magnetic field, and it is much larger under negative magnetic field than that under positive magnetic field. For negative external magnetic field, interfacial exchange coupling gives rise to evident spin splitting for N ≠ 0 Landau levels and a quantum Hall metal state for N = 0 Landau level. Our findings suggest graphene/BiFeO3 heterostructures are promising for spintronics.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000430155900034 Publication Date 2018-04-11  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1530-6984 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 12.712 Times cited 9 Open Access Not_Open_Access  
  Notes This work was supported by National Key Research and Development Program of China (No. 2016YFA0300802) and NSFC (Nos. 11774004 and 11604004). Ministry of Science and Technology of the People's Republic of China, 2016YFA0300802 ; National Natural Science Foundation of China, 11604004 11774004 ; Approved Most recent IF: 12.712  
  Call Number EMAT @ lucian @c:irua:150794 Serial 4923  
Permanent link to this record
 

 
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. pdf  doi
openurl 
  Title Epitaxial stress-free growth of high crystallinity ferroelectric PbZr0.52Ti0.48O3 on GaN/AlGaN/Si(111) substrate Type A1 Journal article
  Year (down) 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 van der Torren, A.J.H.; Liao, Z.; Xu, C.; Gauquelin, N.; Yin, C.; Aarts, J.; van der Molen, S.J. url  doi
openurl 
  Title Formation of a conducting LaAlO3/SrTiO3 interface studied by low-energy electron reflection during growth Type A1 Journal Article
  Year (down) 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  
Permanent link to this record
 

 
Author Zhang, L.; Lin, B.-C.; Wu, Y.-F.; Wu, H.; Huang, T.-W.; Chang, C.-R.; Ke, X.; Kurttepeli, M.; Tendeloo, G.V.; Xu, J.; Yu, D.; Liao, Z.-M. url  doi
openurl 
  Title Electronic Coupling between Graphene and Topological Insulator Induced Anomalous Magnetotransport Properties Type A1 Journal article
  Year (down) 2017 Publication ACS nano Abbreviated Journal Acs Nano  
  Volume 11 Issue 11 Pages 6277-6285  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract It has been theoretically proposed that the spin textures of surface states in a topological insulator can be directly transferred to graphene by means of the proximity effect, which is very important for realizing the two-dimensional topological insulator based on graphene. Here we report the anomalous magnetotransport properties of graphene-topological insulator Bi2Se3 heterojunctions, which are sensitive to the electronic coupling between graphene and the topological surface state. The coupling between the p_z orbitals of graphene and the p orbitals of the surface states on the Bi2Se3 bottom surface can be enhanced by applying a perpendicular negative magnetic field, resulting in a giant negative magnetoresistance at the Dirac point up to about -91%. Obvious resistances dip in the transfer curve at the Dirac point is also observed in the hybrid devices, which is consistent with theoretical predictions of the distorted Dirac bands with nontrivial spin textures inherited from the Bi2Se3 surface states.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000404808000110 Publication Date 2017-05-10  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1936-0851 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 13.942 Times cited 12 Open Access OpenAccess  
  Notes ; This work was supported by National Key Research and Development Program of China (Nos. 2016YFA0300802, 2013CB934600) and NSFC (No. 11234001). ; Approved Most recent IF: 13.942  
  Call Number EMAT @ emat @ c:irua:143192 Serial 4569  
Permanent link to this record
 

 
Author Liao, Z.; Gauquelin, N.; Green, R.J.; Macke, S.; Gonnissen, J.; Thomas, S.; Zhong, Z.; Li, L.; Si, L.; Van Aert, S.; Hansmann, P.; Held, K.; Xia, J.; Verbeeck, J.; Van Tendeloo, G.; Sawatzky, G.A.; Koster, G.; Huijben, M.; Rijnders, G. pdf  doi
openurl 
  Title Thickness dependent properties in oxide heterostructures driven by structurally induced metal-oxygen hybridization variations Type A1 Journal article
  Year (down) 2017 Publication Advanced functional materials Abbreviated Journal Adv Funct Mater  
  Volume 27 Issue 17 Pages 1606717  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Thickness-driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry, or rather to a change of structure with varying film thickness. Here, this study presents direct evidence for the relaxation of oxygen-2p and Mn-3d orbital (p-d) hybridization coupled to the layer-dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic, and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness-dependent p-d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000400449200011 Publication Date 2017-03-15  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1616-301x ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 12.124 Times cited 55 Open Access  
  Notes M.H., G.K., and G.R. acknowledge funding from DESCO program of the Dutch Foundation for Fundamental Research on Matter (FOM) with financial support from the Netherlands Organization for Scientific Research (NWO). This work was funded by the European Union Council under the 7th Framework Program (FP7) Grant No. NMP3-LA-2010-246102 IFOX. J.V. and S.V.A. acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (Grant Nos. G.0044.13N, G.0374.13N, G.0368.15N, and G.0369.15N). The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. N.G. acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant No. 278510 VORTEX. N.G., J.G., S.V.A., and J.V. acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483-ESTEEM2). The Canadian work was supported by NSERC and the Max Planck-UBC Centre for Quantum Materials. Some experiments for this work were performed at the Canadian Light Source, which was funded by the Canada Foundation for Innovation, NSERC, the National Research Council of Canada, the Canadian Institutes of Health Research, the Government of Saskatchewan, Western Economic Diversification Canada, and the University of Saskatchewan. Approved Most recent IF: 12.124  
  Call Number UA @ admin @ c:irua:152640 Serial 5367  
Permanent link to this record
 

 
Author Liao, Z.; Huijben, M.; Zhong, Z.; Gauquelin, N.; Macke, S.; Green, R.J.; Van Aert, S.; Verbeeck, J.; Van Tendeloo, G.; Held, K.; Sawatzky, G.A.; Koster, G.; Rijnders, G. url  doi
openurl 
  Title Controlled lateral anisotropy in correlated manganite heterostructures by interface-engineered oxygen octahedral coupling Type A1 Journal article
  Year (down) 2016 Publication Nature materials Abbreviated Journal Nat Mater  
  Volume 15 Issue 15 Pages 425-431  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract Controlled in-plane rotation of the magnetic easy axis in manganite heterostructures by tailoring the interface oxygen network could allow the development of correlated oxide-based magnetic tunnelling junctions with non-collinear magnetization, with possible practical applications as miniaturized high-switching-speed magnetic random access memory (MRAM) devices. Here, we demonstrate how to manipulate magnetic and electronic anisotropic properties in manganite heterostructures by engineering the oxygen network on the unit-cell level. The strong oxygen octahedral coupling is found to transfer the octahedral rotation, present in the NdGaO3 (NGO) substrate, to the La2/3Sr1/3MnO3 (LSMO) film in the interface region. This causes an unexpected realignment of the magnetic easy axis along the short axis of the LSMO unit cell as well as the presence of a giant anisotropic transport in these ultrathin LSMO films. As a result we possess control of the lateral magnetic and electronic anisotropies by atomic-scale design of the oxygen octahedral rotation.  
  Address MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Wos 000372591700017 Publication Date 2016-03-07  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1476-1122 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 39.737 Times cited 273 Open Access  
  Notes We would like to acknowledge Dr. Evert Houwman for stimulated discussion. M.H., G.K. and G.R. acknowledge funding from DESCO program of the Dutch Foundation for Fundamental Research on Matter (FOM) with financial support from the Netherlands Organization for Scientific Research (NWO). This work was funded by the European Union Council under the 7th Framework Program (FP7) grant nr NMP3-LA-2010- 246102 IFOX. J.V. and S.V.A. acknowledges funding from FWO project G.0044.13N and G. 0368.15N. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. N.G. acknowledges funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant 278510 VORTEX. N.G., S.V.A., J.V. and G.V.T. acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483-ESTEEM2). The Canadian work was supported by NSERC and the Max Planck-UBC Centre for Quantum Materials. Some experiments for this work were performed at the Canadian Light Source, which is funded by the Canada Foundation for Innovation, NSERC, the National Research Council of Canada, the Canadian Institutes of Health Research, the Government of Saskatchewan, Western Economic Diversification Canada, and the University of Saskatchewan. Z.Z. acknowledges funding from the SFB ViCoM (Austrian Science Fund project ID F4103- N13), and Calculations have been done on the Vienna Scientific Cluster (VSC).; esteem2jra2; esteem2jra3 ECASJO_; Approved Most recent IF: 39.737  
  Call Number c:irua:133190 c:irua:133190UA @ admin @ c:irua:133190 Serial 4041  
Permanent link to this record
 

 
Author Liao, Z.L.; Green, R.J.; Gauquelin, N.; Gonnissen, J.; Van Aert, S.; Verbeeck, J.; et al. openurl 
  Title Engineering properties by long range symmetry propagation initiated at perovskite heterostructure interface Type A1 Journal article
  Year (down) 2016 Publication Advanced functional materials Abbreviated Journal Adv Funct Mater  
  Volume Issue Pages 1-25  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which induce an accompanying change in their properties. In perovskite materials, the crystal symmetry can be described by rotations of 6-fold coordinated transition metal oxygen octahedra, which are found to be altered at interfaces. Here, we unravel how the local oxygen octahedral coupling (OOC) at perovskite heterostructural interfaces initiates a different symmetry in epitaxial films and provide design rules to induce various symmetries in thin films by careful selecting appropriate combinations of substrate/buffer/film. Very interestingly we discovered that these combinations lead to symmetry changes throughout the full thickness of the film. Our results provide a deep insight into understanding the origin of induced crystal symmetry in a perovskite heterostructure and an intelligent route to achieve unique functional properties.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Weinheim Editor  
  Language Wos Publication Date  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1616-301x ISBN Additional Links UA library record  
  Impact Factor 12.124 Times cited Open Access  
  Notes Approved Most recent IF: 12.124  
  Call Number UA @ lucian @ c:irua:134842 Serial 4176  
Permanent link to this record
 

 
Author Yan, Y.; Zhou, X.; Jin, H.; Li, C.-Z.; Ke, X.; Van Tendeloo, G.; Liu, K.; Yu, D.; Dressel, M.; Liao, Z.-M. url  doi
openurl 
  Title Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons Type A1 Journal article
  Year (down) 2015 Publication ACS nano Abbreviated Journal Acs Nano  
  Volume 9 Issue 9 Pages 10244-10251  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi2Se3 bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi2Se3 nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi2Se3 nanoribbons grown along the ⟨112̅0⟩ direction. The frequencies of the in-plane Eg2 and out-of-plane A1g1 modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the ⟨112̅0⟩ direction with the curved {0001} surface. In this case, the phonon deformation potential of the Eg2 phonon for 100 nm-thick Bi2Se3 nanoribbon is up to 0.94 cm–1/%, which is twice of that in Bi2Se3 bulk material (0.52 cm–1/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Wos 000363915300079 Publication Date 2015-09-12  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1936-0851;1936-086X; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 13.942 Times cited 14 Open Access  
  Notes Y.Y. would like to thank Xuewen Fu for helpful discussions. This work was supported by MOST (Nos. 2013CB934600, 2013CB932602) and NSFC (Nos. 11274014, 11234001). Approved Most recent IF: 13.942; 2015 IF: 12.881  
  Call Number c:irua:129216 Serial 3963  
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Author Chen, J.J.; Wang, Q.; Meng, J.; Ke, X.; Van Tendeloo, G.; Bie, Y.Q.; Liu, J.; Liu, K.; Liao, Z.M.; Sun, D.; Yu, D.; pdf  url
doi  openurl
  Title Photovoltaic effect and evidence of carrier multiplication in graphene vertical homojunctions with asymmetrical metal contacts Type A1 Journal article
  Year (down) 2015 Publication ACS nano Abbreviated Journal Acs Nano  
  Volume 9 Issue 9 Pages 8851-8858  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metalgraphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000361935800023 Publication Date 2015-08-15  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1936-0851;1936-086X; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 13.942 Times cited 11 Open Access  
  Notes 246791 Countatoms Approved Most recent IF: 13.942; 2015 IF: 12.881  
  Call Number c:irua:127689 Serial 2615  
Permanent link to this record
 

 
Author Chen, J.-J.; Ke, X.; Van Tendeloo, G.; Meng, J.; Zhou, Y.-B.; Liao, Z.-M.; Yu, D.-P. pdf  doi
openurl 
  Title Magnetotransport across the metal-graphene hybrid interface and its modulation by gate voltage Type A1 Journal article
  Year (down) 2015 Publication Nanoscale Abbreviated Journal Nanoscale  
  Volume 7 Issue 7 Pages 5516-5524  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract The graphene-metal contact is very important for optimizing the performance of graphene based electronic devices. However, it is difficult to probe the properties of the graphene/metal interface directly via transport measurements in traditional graphene lateral devices, because the dominated transport channel is graphene, not the interface. Here, we employ the Au/graphene/Au vertical and lateral hybrid structure to unveil the metal-graphene interface properties, where the transport is dominated by the charge carriers across the interface. The magnetoresistance (MR) of Au/monolayer graphene/Au and Au/stacked two-layered graphene/Au devices is measured and modulated by gate voltage, demonstrating that the interface is a device. The gate-tunable MR is identified from the graphene lying on the SiO2 substrate and underneath the top metal electrode. Our unique structures couple the in-plane and out-of-plane transport and display linear MR with small amplitude oscillations at low temperatures. Under a magnetic field, the electronic coupling between the graphene edge states and the electrode leads to the appearance of quantum oscillations. Our results not only provide a new pathway to explore the intrinsic transport mechanism at the graphene/metal interface but also open up new vistas of magnetoelectronics.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Cambridge Editor  
  Language Wos 000351372400050 Publication Date 2015-02-19  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2040-3364;2040-3372; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 7.367 Times cited 3 Open Access  
  Notes 246791 Countatoms Approved Most recent IF: 7.367; 2015 IF: 7.394  
  Call Number c:irua:125533 Serial 1931  
Permanent link to this record
 

 
Author Yan, Y.; Liao, Z.M.; Ke, X.; Van Tendeloo, G.; Wang, Q.; Sun, D.; Yao, W.; Zhou, S.; Zhang, L.; Wu, H.C.; Yu, D.P.; pdf  doi
openurl 
  Title Topological surface state enhanced photothermoelectric effect in Bi2Se3 nanoribbons Type A1 Journal article
  Year (down) 2014 Publication Nano letters Abbreviated Journal Nano Lett  
  Volume 14 Issue 8 Pages 4389-4394  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract The photothermoelectric effect in topological insulator Bi2Se3 nanoribbons is studied. The topological surface states are excited to be spin-polarized by circularly polarized light. Because the direction of the electron spin is locked to its momentum for the spin-helical surface states, the photothermoelectric effect is significantly enhanced as the oriented motions of the polarized spins are accelerated by the temperature gradient. The results are explained based on the microscopic mechanisms of a photon induced spin transition from the surface Dirac cone to the bulk conduction band. The as-reported enhanced photothermoelectric effect is expected to have potential applications in a spin-polarized power source.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Washington Editor  
  Language Wos 000340446200028 Publication Date 2014-07-21  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1530-6984;1530-6992; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 12.712 Times cited 51 Open Access  
  Notes European Research Council under the Seventh Framework Program (FP7); ERC Advanced Grant No. 246791-COUNTATOMS. Approved Most recent IF: 12.712; 2014 IF: 13.592  
  Call Number UA @ lucian @ c:irua:118128 Serial 3678  
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Author Yan, Y.; Wang, L.-X.; Ke, X.; Van Tendeloo, G.; Wu, X.-S.; Yu, D.-P.; Liao, Z.-M. pdf  url
doi  openurl
  Title High-mobility Bi2Se3 nanoplates manifesting quantum oscillations of surface states in the sidewalls Type A1 Journal article
  Year (down) 2014 Publication Scientific reports Abbreviated Journal Sci Rep-Uk  
  Volume 4 Issue Pages 3817-7  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Magnetotransport measurements of topological insulators are very important to reveal the exotic topological surface states for spintronic applications. However, the novel properties related to the surface Dirac fermions are usually accompanied by a large linear magnetoresistance under perpendicular magnetic field, which makes the identification of the surface states obscure. Here, we report prominent Shubnikov-de Haas (SdH) oscillations under an in-plane magnetic field, which are identified to originate from the surface states in the sidewalls of topological insulator Bi2Se3 nanoplates. Importantly, the SdH oscillations appear with a dramatically weakened magnetoresistance background, offering an easy path to probe the surface states directly when the coexistence of surface states and bulk conduction is inevitable. Moreover, under a perpendicular magnetic field, the oscillations in Hall conductivity have peak-to-valley amplitudes of 2 e(2)/h, giving confidence to achieve a quantum Hall effect in this system. A cross-section view of the nanoplate shows that the sidewall is (015) facet dominant and therefore forms a 586 angle with regard to the top/ bottom surface instead of being perpendicular; this gives credit to the surface states' behavior as two-dimensional transport.  
  Address  
  Corporate Author Thesis  
  Publisher Nature Publishing Group Place of Publication London Editor  
  Language Wos 000330044700008 Publication Date 2014-01-22  
  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 31 Open Access  
  Notes ERC grant Nu246791 – COUNTATOMS Approved Most recent IF: 4.259; 2014 IF: 5.578  
  Call Number UA @ lucian @ c:irua:114815 Serial 1436  
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