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Author Béché, A.; Van Boxem, R.; Van Tendeloo, G.; Verbeeck, J.
Title Magnetic monopole field exposed by electrons Type A1 Journal article
Year 2014 Publication Nature physics Abbreviated Journal (up) Nat Phys
Volume 10 Issue 1 Pages 26-29
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The experimental search for magnetic monopole particles(1-3) has, so far, been in vain. Nevertheless, these elusive particles of magnetic charge have fuelled a rich field of theoretical study(4-10). Here, we created an approximation of a magnetic monopole in free space at the end of a long, nanoscopically thin magnetic needle(11). We experimentally demonstrate that the interaction of this approximate magnetic monopole field with a beam of electrons produces an electron vortex state, as theoretically predicted for a true magnetic monopole(3,11-18). This fundamental quantum mechanical scattering experiment is independent of the speed of the electrons and has consequences for all situations where electrons meet such monopole magnetic fields, as, for example, in solids. The set-up not only shows an attractive way to produce electron vortex states but also provides a unique insight into monopole fields and shows that electron vortices might well occur in unexplored solid-state physics situations.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000328940100012 Publication Date 2013-11-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473;1745-2481; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 22.806 Times cited 131 Open Access
Notes Vortex; Countatoms; Fwo ECASJO_; Approved Most recent IF: 22.806; 2014 IF: 20.147
Call Number UA @ lucian @ c:irua:113740UA @ admin @ c:irua:113740 Serial 1885
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Author Lukyanchuk, I.; Vinokur, V.M.; Rydh, A.; Xie, R.; Milošević, M.V.; Welp, U.; Zach, M.; Xiao, Z.L.; Crabtree, G.W.; Bending, S.J.; Peeters, F.M.; Kwok, W.K.
Title Rayleigh instability of confined vortex droplets in critical superconductors Type A1 Journal article
Year 2015 Publication Nature physics Abbreviated Journal (up) Nat Phys
Volume 11 Issue 11 Pages 21-25
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Depending on the Ginzburg-Landau parameter kappa, superconductors can either be fully diamagnetic if kappa < 1/root 2 (type I superconductors) or allow magnetic flux to penetrate through Abrikosov vortices if kappa > 1/root 2 (type II superconductors; refs 1,2). At the Bogomolny critical point, kappa = kappa(c) = 1/root 2, a state that is infinitely degenerate with respect to vortex spatial configurations arises(3,4). Despite in-depth investigations of conventional type I and type II superconductors, a thorough understanding of the magnetic behaviour in the near-Bogomolny critical regime at kappa similar to kappa(c) remains lacking. Here we report that in confined systems the critical regime expands over a finite interval of kappa forming a critical superconducting state. We show that in this state, in a sample with dimensions comparable to the vortex core size, vortices merge into a multi-quanta droplet, which undergoes Rayleigh instability(5) on increasing kappa and decays by emitting single vortices. Superconducting vortices realize Nielsen-Olesen singular solutions of the Abelian Higgs model, which is pervasive in phenomena ranging from quantum electrodynamics to cosmology(6-9). Our study of the transient dynamics of Abrikosov-Nielsen-Olesen vortices in systems with boundaries promises access to non-trivial effects in quantum field theory by means of bench-top laboratory experiments.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000346831100018 Publication Date 2014-11-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473;1745-2481; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 22.806 Times cited 20 Open Access
Notes ; We would like to thank N. Nekrasov for illuminating discussions. The work was supported by the US Department of Energy, Office of Science Materials Sciences and Engineering Division (V.M.V., W.K.K., U.W., R.X., M.Z., Z.L.X., G.W.C. and partially I.L. through the Materials Theory Institute), by FP7-IRSES-SIMTECH and ITN-NOTEDEV programs (I.L.), and by the Flemish Science Foundation (FWO-Vlaanderen) (M.V.M. and F.M.P.). ; Approved Most recent IF: 22.806; 2015 IF: 20.147
Call Number c:irua:122791 c:irua:122791 Serial 2815
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Author Roditchev, D.; Brun, C.; Serrier-Garcia, L.; Cuevas, J.C.; Bessa, V.H.L.; Milošević, M.V.; Debontridder, F.; Stolyarov, V.; Cren, T.
Title Direct observation of Josephson vortex cores Type A1 Journal article
Year 2015 Publication Nature physics Abbreviated Journal (up) Nat Phys
Volume 11 Issue 11 Pages 332-337
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Superconducting correlations may propagate between two superconductors separated by a tiny insulating or metallic barrier, allowing a dissipationless electric current to flow(1,2). In the presence of a magnetic field, the maximum supercurrent oscillates(3) and each oscillation corresponding to the entry of one Josephson vortex into the barrier(4). Josephson vortices are conceptual blocks of advanced quantum devices such as coherent terahertz generators(5) or qubits for quantum computing(6), in which on-demand generation and control is crucial. Here, we map superconducting correlations inside proximity Josephson junctions(7) using scanning tunnelling microscopy. Unexpectedly, we find that such Josephson vortices have real cores, in which the proximity gap is locally suppressed and the normal state recovered. By following the Josephson vortex formation and evolution we demonstrate that they originate from quantum interference of Andreev quasiparticles(8), and that the phase portraits of the two superconducting quantum condensates at edges of the junction decide their generation, shape, spatial extent and arrangement. Our observation opens a pathway towards the generation and control of Josephson vortices by applying supercurrents through the superconducting leads of the junctions, that is, by purely electrical means without any need for a magnetic field, which is a crucial step towards high-density on-chip integration of superconducting quantum devices.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000352163100016 Publication Date 2015-02-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473;1745-2481; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 22.806 Times cited 102 Open Access
Notes T.C., C.B., F.D., V.S. and D.R. acknowledge financial support from the French ANR project and the French-Russian program PICS-CNRS/RAS. The authors also thank V. Cherkez for assistance during experiments and V. Vinokur (Argonne National Laboratory, Illinois USA) and A. Buzdin (University of Bordeaux 1, France) for stimulating discussions. J.C.C. acknowledges financial support from the Spanish MICINN (Contract No. FIS2011-28851-C1). V.H.L.B. acknowledges support from CNPq Brazil and productive discussions with Prof. A. Chaves (UFC, Brazil). M.V.M. acknowledges support from Research Foundation Flanders (FWO-Vlaanderen) and CAPES Brazil (PVE project BEX1392/11-5). Approved Most recent IF: 22.806; 2015 IF: 20.147
Call Number c:irua:132524 c:irua:132524 Serial 3943
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Author Mao, J.; Jiang, Y.; Moldovan, D.; Li, G.; Watanabe, K.; Taniguchi, T.; Masir, M.R.; Peeters, F.M.; Andrei, E.Y.
Title Realization of a tunable artificial atom at a supercritically charged vacancy in graphene Type A1 Journal article
Year 2016 Publication Nature physics Abbreviated Journal (up) Nat Phys
Volume 12 Issue 12 Pages 545-549
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Graphene’s remarkable electronic properties have fuelled the vision of a graphene-based platform for lighter, faster and smarter electronics and computing applications. One of the challenges is to devise ways to tailor graphene’s electronic properties and to control its charge carriers. Here we show that a single-atom vacancy in graphene can stably host a local charge and that this charge can be gradually built up by applying voltage pulses with the tip of a scanning tunnelling microscope. The response of the conduction electrons in graphene to the local charge is monitored with scanning tunnelling and Landau level spectroscopy, and compared to numerical simulations. As the charge is increased, its interaction with the conduction electrons undergoes a transition into a supercritical regime where itinerant electrons are trapped in a sequence of quasi-bound states which resemble an artificial atom. The quasi-bound electron states are detected by a strong enhancement of the density of states within a disc centred on the vacancy site which is surrounded by halo of hole states. We further show that the quasi-bound states at the vacancy site are gate tunable and that the trapping mechanism can be turned on and off, providing a mechanism to control and guide electrons in graphene.
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Publisher Place of Publication Editor
Language Wos 000377475700011 Publication Date 2016-02-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 22.806 Times cited 93 Open Access
Notes ; Funding was provided by DOE-FG02-99ER45742 (STM/STS), NSF DMR 1207108 (fabrication and characterization). Theoretical work supported by ESF-EUROCORES-EuroGRAPHENE, FWO-VI and Methusalem programme of the Flemish government. We thank V. F. Libisch, M. Pereira and E. Rossi for useful discussions. ; Approved Most recent IF: 22.806
Call Number c:irua:134210 Serial 4011
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Author Partoens, B.
Title Spinorbit interactions : hide and seek Type A1 Journal article
Year 2014 Publication Nature physics Abbreviated Journal (up) Nat Phys
Volume 10 Issue Pages 333-334
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract It is commonly believed that solids with spatial inversion symmetry do not display spinorbit effects. However, first-principles calculations now reveal unexpected spin structure for centrosymmetric crystals
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000335371200003 Publication Date 2014-04-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473; 1745-2481 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 22.806 Times cited 8 Open Access
Notes Approved Most recent IF: 22.806; 2014 IF: 20.147
Call Number UA @ lucian @ c:irua:141068 Serial 4608
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Author Wang, D.; Dasgupta, T.; van der Wee, E.B.; Zanaga, D.; Altantzis, T.; Wu, Y.; Coli, G.M.; Murray, C.B.; Bals, S.; Dijkstra, M.; van Blaaderen, A.
Title Binary icosahedral clusters of hard spheres in spherical confinement Type A1 Journal article
Year 2020 Publication Nature Physics Abbreviated Journal (up) Nat Phys
Volume Issue Pages 1-9
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Applied Electrochemistry & Catalysis (ELCAT)
Abstract The influence of geometry on the local and global packing of particles is important to many fundamental and applied research themes, such as the structure and stability of liquids, crystals and glasses. Here we show by experiments and simulations that a binary mixture of hard-sphere-like nanoparticles crystallizing into a MgZn(2)Laves phase in bulk spontaneously forms icosahedral clusters in slowly drying droplets. Using advanced electron tomography, we are able to obtain the real-space coordinates of all the spheres in the icosahedral clusters of up to about 10,000 particles. The local structure of 70-80% of the particles became similar to that of the MgCu(2)Laves phase. These observations are important for photonic applications. In addition, we observed in simulations that the icosahedral clusters nucleated away from the spherical boundary, which is distinctly different from that of the single species clusters. Our findings open the way for particle-level studies of nucleation and growth of icosahedral clusters, and of binary crystallization. The authors investigate out-of-equilibrium crystallization of a binary mixture of sphere-like nanoparticles in small droplets. They observe the spontaneous formation of an icosahedral structure with stable MgCu(2)phases, which are promising for photonic applications.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000564497300002 Publication Date 2020-08-31
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1745-2473; 1745-2481 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 19.6 Times cited 38 Open Access OpenAccess
Notes ; D.W., E.B.v.d.W. and A.v.B. acknowledge partial financial support from the European Research Council under the European Union's Seventh Framework Programme (FP-2007-2013)/ERC Advanced Grant Agreement 291667 HierarSACol. T.D. and M. D. acknowledge financial support from the Industrial Partnership Programme, 'Computational Sciences for Energy Research' (grant number 13CSER025), of the Netherlands Organization for Scientific Research (NWO), which was co-financed by Shell Global Solutions International BV G.M.C. was also financially supported by NWO. S.B. acknowledges financial support from ERC Consolidator Grant Number 815128 REALNANO. T.A. acknowledges a post-doctoral grant from the Research Foundation Flanders (FWO, Belgium). C.B.M. and Y.W. acknowledge support for materials synthesis from the Office of Naval Research Multidisciplinary University Research Initiative Award ONR N00014-18-1-2497. G. A. Blab is gratefully acknowledged for 3D printing numerous truncated tetrahedra, which increased our understanding of the connection between the binary icosahedral cluster and Laves phase structures. N. Tasios is sincerely thanked for providing the code for the diffraction pattern calculation. M. Hermes is sincerely thanked for providing interactive views of the structures in this work. We thank G. van Tendeloo, M. Engel, J. Wang, S. Dussi, L. Filion, E. Boattini, S. Paliwal, N. Tasios, B. van der Meer, I. Lobato, J. Wu and L. Laurens for fruitful discussions. We acknowledge the EM Square centre at Utrecht University for the access to the microscopes. ; sygma Approved Most recent IF: 19.6; 2020 IF: 22.806
Call Number UA @ admin @ c:irua:172044 Serial 6460
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Author Loquet, J.-P.; Perret, J.; Fompeyrine, J.; Mächler, E.; Seo, J.W.; Van Tendeloo, G.
Title Doubling the critical temperature of La1.9Sr0.1CuO4 using epitaxial strain Type A1 Journal article
Year 1998 Publication Nature Abbreviated Journal (up) Nature
Volume 394 Issue Pages 453-456
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
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Publisher Place of Publication Editor
Language Wos 000075080400044 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 404 Open Access
Notes Approved Most recent IF: 40.137; 1998 IF: 28.833
Call Number UA @ lucian @ c:irua:25676 Serial 757
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Author Geim, A.K.; Dubonos, S.V.; Grigorieva, I.V.; Novoselov, K.S.; Peeters, F.M.; Schweigert, V.A.
Title Non-quantized penetration of magnetic field in the vortex state of superconductors Type A1 Journal article
Year 2000 Publication Nature Abbreviated Journal (up) Nature
Volume 407 Issue Pages 55-57
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000089124000037 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 155 Open Access
Notes Approved Most recent IF: 40.137; 2000 IF: 25.814
Call Number UA @ lucian @ c:irua:34356 Serial 2350
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Author Geim, A.K.; Grigorieva, I.V.; Dubonos, S.V.; Lok, J.G.S.; Maan, J.C.; Filippov, A.E.; Peeters, F.M.
Title Phase transitions in individual sub-micrometre superconductors Type A1 Journal article
Year 1997 Publication Nature Abbreviated Journal (up) Nature
Volume 390 Issue Pages 259-262
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos A1997YG66700054 Publication Date 2002-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 370 Open Access
Notes Approved Most recent IF: 40.137; 1997 IF: 27.368
Call Number UA @ lucian @ c:irua:19265 Serial 2595
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Author Verbeeck, J.; Tian, H.; Schattschneider, P.
Title Production and application of electron vortex beams Type A1 Journal article
Year 2010 Publication Nature Abbreviated Journal (up) Nature
Volume 467 Issue 7313 Pages 301-304
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Vortex beams (also known as beams with a phase singularity) consist of spiralling wavefronts that give rise to angular momentum around the propagation direction. Vortex photon beams are widely used in applications such as optical tweezers to manipulate micrometre-sized particles and in micro-motors to provide angular momentum1, 2, improving channel capacity in optical3 and radio-wave4 information transfer, astrophysics5 and so on6. Very recently, an experimental realization of vortex beams formed of electrons was demonstrated7. Here we describe the creation of vortex electron beams, making use of a versatile holographic reconstruction technique in a transmission electron microscope. This technique is a reproducible method of creating vortex electron beams in a conventional electron microscope. We demonstrate how they may be used in electron energy-loss spectroscopy to detect the magnetic state of materials and describe their properties. Our results show that electron vortex beams hold promise for new applications, in particular for analysing and manipulating nanomaterials, and can be easily produced.
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Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000281824900033 Publication Date 2010-09-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836;1476-4687; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 626 Open Access
Notes Esteem 026019; Fwo Approved Most recent IF: 40.137; 2010 IF: 36.104
Call Number UA @ lucian @ c:irua:84878UA @ admin @ c:irua:84878 Serial 2720
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Author Van Aert, S.; Batenburg, K.J.; Rossell, M.D.; Erni, R.; Van Tendeloo, G.
Title Three-dimensional atomic imaging of crystalline nanoparticles Type A1 Journal article
Year 2011 Publication Nature Abbreviated Journal (up) Nature
Volume 470 Issue 7334 Pages 374-377
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Determining the three-dimensional (3D) arrangement of atoms in crystalline nanoparticles is important for nanometre-scale device engineering and also for applications involving nanoparticles, such as optoelectronics or catalysis. A nanoparticles physical and chemical properties are controlled by its exact 3D morphology, structure and composition1. Electron tomography enables the recovery of the shape of a nanoparticle from a series of projection images2, 3, 4. Although atomic-resolution electron microscopy has been feasible for nearly four decades, neither electron tomography nor any other experimental technique has yet demonstrated atomic resolution in three dimensions. Here we report the 3D reconstruction of a complex crystalline nanoparticle at atomic resolution. To achieve this, we combined aberration-corrected scanning transmission electron microscopy5, 6, 7, statistical parameter estimation theory8, 9 and discrete tomography10, 11. Unlike conventional electron tomography, only two images of the targeta silver nanoparticle embedded in an aluminium matrixare sufficient for the reconstruction when combined with available knowledge about the particles crystallographic structure. Additional projections confirm the reliability of the result. The results we present help close the gap between the atomic resolution achievable in two-dimensional electron micrographs and the coarser resolution that has hitherto been obtained by conventional electron tomography.
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Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000287409100037 Publication Date 2011-02-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836;1476-4687; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 341 Open Access
Notes Esteem 026019 Approved Most recent IF: 40.137; 2011 IF: 36.280
Call Number UA @ lucian @ c:irua:86745 Serial 3644
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Author Zhou, K.-G.; Vasu, K.S.; Cherian, C.T.; Neek-Amal, M.; Zhang, J.C.; Ghorbanfekr-Kalashami, H.; Huang, K.; Marshall, O.P.; Kravets, V.G.; Abraham, J.; Su, Y.; Grigorenko, A.N.; Pratt, A.; Geim, A.K.; Peeters, F.M.; Novoselov, K.S.; Nair, R.R.
Title Electrically controlled water permeation through graphene oxide membranes Type A1 Journal article
Year 2018 Publication Nature Abbreviated Journal (up) Nature
Volume 559 Issue 7713 Pages 236-+
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies(1-7). Previous attempts to control water permeation through membranes (mainly polymeric ones) have concentrated on modulating the structure of the membrane and the physicochemical properties of its surface by varying the pH, temperature or ionic strength(3,8). Electrical control over water transport is an attractive alternative; however, theory and simulations(9-14) have often yielded conflicting results, from freezing of water molecules to melting of ice(14-16) under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes(17-21). Such membranes have previously been shown to exhibit ultrafast permeation of water(17,22) and molecular sieving properties(18,21), with the potential for industrial-scale production. To achieve electrical control over water permeation, we create conductive filaments in the graphene oxide membranes via controllable electrical breakdown. The electric field that concentrates around these current-carrying filaments ionizes water molecules inside graphene capillaries within the graphene oxide membranes, which impedes water transport. We thus demonstrate precise control of water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for developing smart membrane technologies for artificial biological systems, tissue engineering and filtration.
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Publisher Place of Publication London Editor
Language Wos 000438240900052 Publication Date 2018-07-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 216 Open Access
Notes ; This work was supported by the Royal Society, Engineering and Physical Sciences Research Council, UK (EP/K016946/1, EP/N013670/1 and EP/P00119X/1), British Council (award reference number 279336045), European Research Council (contract 679689) and Lloyd's Register Foundation. We thank J. Waters for assisting with X-ray measurements and G. Yu for electrical measurements. ; Approved Most recent IF: 40.137
Call Number UA @ lucian @ c:irua:152420UA @ admin @ c:irua:152420 Serial 5096
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Author Chaves, A.; Neilson, D.
Title Exotic state seen at high temperatures Type Editorial
Year 2019 Publication Nature Abbreviated Journal (up) Nature
Volume 574 Issue 7776 Pages 39-40
Keywords Editorial; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The phenomenon of Bose-Einstein condensation is typically limited to extremely low temperatures. The effect has now been spotted at much higher temperatures for particles called excitons in atomically thin semiconductors.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000488832500022 Publication Date 2019-10-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited 2 Open Access
Notes ; ; Approved Most recent IF: 40.137
Call Number UA @ admin @ c:irua:163739 Serial 5413
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Author Mao, J.; Milovanović, S.P.; Andelkovic, M.; Lai, X.; Cao, Y.; Watanabe, K.; Taniguchi, T.; Covaci, L.; Peeters, F.M.; Geim, A.K.; Jiang, Y.; Andrei, E.Y.
Title Evidence of flat bands and correlated states in buckled graphene superlattices Type A1 Journal article
Year 2020 Publication Nature Abbreviated Journal (up) Nature
Volume 584 Issue 7820 Pages 215-220
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract Two-dimensional atomic crystals can radically change their properties in response to external influences, such as substrate orientation or strain, forming materials with novel electronic structure(1-5). An example is the creation of weakly dispersive, 'flat' bands in bilayer graphene for certain 'magic' angles of twist between the orientations of the two layers(6). The quenched kinetic energy in these flat bands promotes electron-electron interactions and facilitates the emergence of strongly correlated phases, such as superconductivity and correlated insulators. However, the very accurate fine-tuning required to obtain the magic angle in twisted-bilayer graphene poses challenges to fabrication and scalability. Here we present an alternative route to creating flat bands that does not involve fine-tuning. Using scanning tunnelling microscopy and spectroscopy, together with numerical simulations, we demonstrate that graphene monolayers placed on an atomically flat substrate can be forced to undergo a buckling transition(7-9), resulting in a periodically modulated pseudo-magnetic field(10-14), which in turn creates a 'post-graphene' material with flat electronic bands. When we introduce the Fermi level into these flat bands using electrostatic doping, we observe a pseudogap-like depletion in the density of states, which signals the emergence of a correlated state(15-17). This buckling of two-dimensional crystals offers a strategy for creating other superlattice systems and, in particular, for exploring interaction phenomena characteristic of flat bands. Buckled monolayer graphene superlattices are found to provide an alternative to twisted bilayer graphene for the study of flat bands and correlated states in a carbon-based material.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000559831500012 Publication Date 2020-08-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 64.8 Times cited 109 Open Access Not_Open_Access
Notes ; ; Approved Most recent IF: 64.8; 2020 IF: 40.137
Call Number UA @ admin @ c:irua:171150 Serial 6513
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Author Samae, V.; Cordier, P.; Demouchy, S.; Bollinger, C.; Gasc, J.; Koizumi, S.; Mussi, A.; Schryvers, D.; Idrissi, H.
Title Stress-induced amorphization triggers deformation in the lithospheric mantle Type A1 Journal article
Year 2021 Publication Nature Abbreviated Journal (up) Nature
Volume 591 Issue 7848 Pages 82-86
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The mechanical properties of olivine-rich rocks are key to determining the mechanical coupling between Earth's lithosphere and asthenosphere. In crystalline materials, the motion of crystal defects is fundamental to plastic flow(1-4.) However, because the main constituent of olivine-rich rocks does not have enough slip systems, additional deformation mechanisms are needed to satisfy strain conditions. Experimental studies have suggested a non-Newtonian, grain-size-sensitive mechanism in olivine involving grain-boundary sliding(5,6). However, very few microstructural investigations have been conducted on grain-boundary sliding, and there is no consensus on whether a single or multiple physical mechanisms are at play. Most importantly, there are no theoretical frameworks for incorporating the mechanics of grain boundaries in polycrystalline plasticity models. Here we identify a mechanism for deformation at grain boundaries in olivine-rich rocks. We show that, in forsterite, amorphization takes place at grain boundaries under stress and that the onset of ductility of olivine-rich rocks is due to the activation of grain-boundary mobility in these amorphous layers. This mechanism could trigger plastic processes in the deep Earth, where high-stress conditions are encountered (for example, at the brittle-plastic transition). Our proposed mechanism is especially relevant at the lithosphere-asthenosphere boundary, where olivine reaches the glass transition temperature, triggering a decrease in its viscosity and thus promoting grain-boundary sliding.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000626921700014 Publication Date 2021-03-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 40.137 Times cited Open Access OpenAccess
Notes Approved Most recent IF: 40.137
Call Number UA @ admin @ c:irua:176656 Serial 6738
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Author Tong, J.; Fu, Y.; Domaretskiy, D.; Della Pia, F.; Dagar, P.; Powell, L.; Bahamon, D.; Huang, S.; Xin, B.; Costa Filho, R.N.; Vega, L.F.; Grigorieva, I.V.; Peeters, F.M.; Michaelides, A.; Lozada-Hidalgo, M.
Title Control of proton transport and hydrogenation in double-gated graphene Type A1 Journal Article
Year 2024 Publication Nature Abbreviated Journal (up) Nature
Volume 630 Issue 8017 Pages 619-624
Keywords A1 Journal Article; Condensed Matter Theory (CMT) ;
Abstract The basal plane of graphene can function as a selective barrier that is permeable to protons but impermeable to all ions and gases, stimulating its use in applications such as membranes, catalysis and isotope separation. Protons can chemically adsorb on graphene and hydrogenate it, inducing a conductor–insulator transition that has been explored intensively in graphene electronic devices. However, both processes face energy barriersand various strategies have been proposed to accelerate proton transport, for example by introducing vacancies, incorporating catalytic metalsor chemically functionalizing the lattice. But these techniques can compromise other properties, such as ion selectivity or mechanical stability. Here we show that independent control of the electric field,<italic>E</italic>, at around 1 V nm<sup>−1</sup>, and charge-carrier density,<italic>n</italic>, at around 1 × 10<sup>14</sup> cm<sup>−2</sup>, in double-gated graphene allows the decoupling of proton transport from lattice hydrogenation and can thereby accelerate proton transport such that it approaches the limiting electrolyte current for our devices. Proton transport and hydrogenation can be driven selectively with precision and robustness, enabling proton-based logic and memory graphene devices that have on–off ratios spanning orders of magnitude. Our results show that field effects can accelerate and decouple electrochemical processes in double-gated 2D crystals and demonstrate the possibility of mapping such processes as a function of<italic>E</italic>and<italic>n</italic>, which is a new technique for the study of 2D electrode–electrolyte interfaces.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date 2024-06-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0028-0836 ISBN Additional Links
Impact Factor 64.8 Times cited Open Access
Notes This work was supported by UKRI (EP/X017745: M.L.-H; EP/X035891: A.M.), the Directed Research Projects Program of the Research and Innovation Center for Graphene and 2D Materials at Khalifa University (RIC2D-D001: M.L.-H., L.F.V. and D.B.), The Royal Society (URF\R1\201515: M.L.-H.) and the European Research Council (101071937: A.M.). Part of this work was supported by the Flemish Science Foundation (FWO-Vl, G099219N). A.M. acknowledges access to the UK national high-performance computing service (ARCHER2). Approved Most recent IF: 64.8; 2024 IF: 40.137
Call Number CMT @ cmt @ Serial 9247
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