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Author | Li, L.L.; Bacaksiz, C.; Nakhaee, M.; Pentcheva, R.; Peeters, F.M.; Yagmurcukardes, M. | ||||
Title | Single-layer Janus black arsenic-phosphorus (b-AsP): optical dichroism, anisotropic vibrational, thermal, and elastic properties | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 13 | Pages | 134102-134109 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | By using density functional theory (DFT) calculations, we predict a puckered, dynamically stable Janus single-layer black arsenic-phosphorus (b-AsP), which is composed of two different atomic sublayers, arsenic and phosphorus atoms. The calculated phonon spectrum reveals that Janus single-layer b-AsP is dynamically stable with either pure or coupled optical phonon branches arising from As and P atoms. The calculated Raman spectrum indicates that due to the relatively strong P-P bonds, As atoms have no contribution to the highfrequency optical vibrations. In addition, the orientation-dependent isovolume heat capacity reveals anisotropic contributions of LA and TA phonon branches to the low-temperature thermal properties. Unlike pristine single layers of b-As and b-P, Janus single-layer b-AsP exhibits additional out-of-plane asymmetry which leads to important consequences for its electronic, optical, and elastic properties. In contrast to single-layer b-As, Janus single-layer b-AsP is found to possess a direct band gap dominated by the P atoms. Moreover, real and imaginary parts of the dynamical dielectric function, including excitonic effects, reveal the highly anisotropic optical feature of the Janus single-layer. A tight-binding (TB) model is also presented for Janus single-layer b-AsP, and it is shown that, with up to seven nearest hoppings, the TB model reproduces well the DFT band structure in the low-energy region around the band gap. This TB model can be used in combination with the Green's function approach to study, e.g., quantum transport in finite systems based on Janus single-layer b-AsP. Furthermore, the linear-elastic properties of Janus single-layer b-AsP are investigated, and the orientation-dependent in-plane stiffness and Poisson ratio are calculated. It is found that the Janus single layer exhibits strong in-plane anisotropy in its Poisson ratio much larger than that of single-layer b-P. This Janus single layer is relevant for promising applications in optical dichroism and anisotropic nanoelasticity. | ||||
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Language | Wos | 000524531900001 | Publication Date | 2020-04-09 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 39 | Open Access | |
Notes | ; This work was supported by the German Science Foundation (DFG) within SFB/TRR80 (project G3) and the FLAGERA project TRANS-2D-TMD. M.Y. was supported by a postdoctoral fellowship from the Flemish Science Foundation (FWO-Vl). Computational resources were provided by the Flemish Supercomputer Center (VSC) and Leibniz Supercomputer Centrum (project pr87ro). ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:168554 | Serial | 6602 | ||
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Author | Osca, J.; Sorée, B. | ||||
Title | Skyrmion spin transfer torque due to current confined in a nanowire | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 12 | Pages | 125436 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | In this work we compute the torque field present in a ferromagnet in contact with a metallic nanowire when a skyrmion is present. If the nanowire is narrow enough, then the current is carried by a single conduction band. In this regime the classical torque model breaks down and we show that a skyrmion driven by spin transfer torque moves in a different direction than predicted by the classical model. However, the amount of charge current required to move a skyrmion with a certain velocity in the single-band regime is similar to a classical model of torque where it is implicitly assumed current transport by many conduction bands. The single-band regime is more efficient creating spin current from charge current because of the perfect polarization of the single band but is less efficient creating torque from spin current. Nevertheless, it is possible to take profit of the single-band regime to move skyrmions even with no net charge or spin current flowing between the device contacts. We have also been able to recover the classical limit considering an ensemble of only a few electronic states. In this limit we have discovered that electron diffusion needs to be considered even in ballistic nanowires due the effect of the skyrmion structure on the electron current. | ||||
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Language | Wos | 000573775300004 | Publication Date | 2020-09-30 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | Open Access | ||
Notes | ; The authors thanks Llorenc Serra for useful discussion on the conduction electron quantum model. We also want to show gratitude to Dimitrios Andrikopoulos for sharing his knowledge about the available bibliography and to F. J. P. van Duijn for his comments on earlier versions of this manuscript. We acknowledge the Horizon 2020 project SKYTOP “Skyrmion-Topological Insulator and Weyl Semimetal Technology” (FETPROACT-2018-01, No. 824123). Finally, J.O. also acknowledges the postdoctoral fellowship provided by KU Leuven. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:172727 | Serial | 6604 | ||
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Author | Zhang, L.; Zhang, Y.-Y.; Zha, G.-Q.; Milošević, M.V.; Zhou, S.-P. | ||||
Title | Skyrmionic chains and lattices in s plus id superconductors | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 6 | Pages | 064501 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | We report characteristic vortex configurations in s + id superconductors with time-reversal symmetry breaking, exposed to magnetic field. A vortex in the s + id state tends to have an opposite phase winding between s- and d-wave condensates. We find that this peculiar feature together with the competition between s- and d-wave symmetry results in three distinct classes of vortical configurations. When either s or d condensate absolutely dominates, vortices form a conventional lattice. However, when one condensate is relatively dominant, vortices organize in chains that exhibit skyrmionic character, separating the chiral components of the s +/- id order parameter into domains within and outside the chain. Such skyrmionic chains are found stable even at high magnetic field. When s and d condensates have comparable strength, vortices split cores in two chiral components to form full-fledged skyrmions, i.e., coreless topological structures with an integer topological charge, organized in a lattice. We provide characteristic magnetic field distributions of all states, enabling their identification in, e.g., scanning Hall probe and scanning SQUID experiments. These unique vortex states are relevant for high-T-c cuprate and iron-based superconductors, where the relative strength of competing pairing symmetries is expected to be tuned by temperature and/or doping level, and can help distinguish s + is and s + id superconducting phases. | ||||
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Language | Wos | 000510745600005 | Publication Date | 2020-02-03 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 7 | Open Access | |
Notes | ; The authors acknowledge useful discussions with Yong-Ping Zhang. This research was supported by the National Natural Science Foundation of China under Grants No. 61571277 and No. 61771298. L.-F.Z. and M.V.M. acknowledge support from Research Foundation-Flanders (FWO-Vlaanderen). ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:166507 | Serial | 6605 | ||
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Author | Menezes, R.M.; de Souza Silva, C.C.; Milošević, M.V. | ||||
Title | Spin textures in chiral magnetic monolayers with suppressed nearest-neighbor exchange | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 21 | Pages | 214429-9 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | High tunability of two-dimensional magnetic materials (by strain, gating, heterostructuring, or otherwise) provides unique conditions for studying versatile magnetic properties and controlling emergent magnetic phases. Expanding the scope of achievable magnetic phenomena in such materials is important for both fundamental and technological advances. Here we perform atomistic spin-dynamics simulations to explore the (chiral) magnetic phases of atomic monolayers in the limit of suppressed first-neighbors exchange interaction. We report the rich phase diagram of exotic magnetic configurations, obtained for both square and honeycomb lattice symmetries, comprising coexistence of ferromagnetic and antiferromagnetic spin cycloids, as well as multiple types of magnetic skyrmions. We perform a minimum-energy path analysis for the skyrmion collapse to evaluate the stability of such topological objects and reveal that magnetic monolayers could be good candidates to host the antiferromagnetic skyrmions that are experimentally evasive to date. | ||||
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Language | Wos | 000540910100002 | Publication Date | 2020-06-18 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 1 | Open Access | |
Notes | ; This work was supported by the Research Foundation-Flanders (FWO-Vlaanderen) and Brazilian Agencies FACEPE (under Grant No. APQ-0198-1.05/14), CAPES, and CNPq. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:170176 | Serial | 6610 | ||
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Author | Yagmurcukardes, M.; Peeters, F.M. | ||||
Title | Stable single layer of Janus MoSO: strong out-of-plane piezoelectricity | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 15 | Pages | 155205-155208 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Using density functional theory based first-principles calculations, we predict the dynamically stable 1H phase of a Janus single layer composed of S-Mo-O atomic layers. It is an indirect band gap semiconductor exhibiting strong polarization arising from the charge difference on the two surfaces. In contrast to 1H phases of MoS2 and MoO2, Janus MoSO is found to possess four Raman active phonon modes and a large out-of-plane piezoelectric coefficient which is absent in fully symmetric single layers of MoS2 and MoO2. We investigated the electronic and phononic properties under applied biaxial strain and found an electronic phase transition with tensile strain while the conduction band edge displays a shift when under compressive strain. Furthermore, single-layer MoSO exhibits phononic stability up to 5% of compressive and 11% of tensile strain with significant phonon shifts. The phonon instability is shown to arise from the soft in-plane and out-of-plane acoustic modes at finite wave vector. The large strain tolerance of Janus MoSO is important for nanoelastic applications. In view of the dynamical stability even under moderate strain, we expect that Janus MoSO can be fabricated in the common 1H phase with a strong out-of-plane piezoelectric coefficient. | ||||
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Language | Wos | 000528507900003 | Publication Date | 2020-04-24 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 66 | Open Access | |
Notes | ; Computational resources were provided by the Flemish Supercomputer Center (VSC). M.Y. is supported by the Flemish Science Foundation (FWO-Vl) through a postdoctoral fellowship. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:169566 | Serial | 6614 | ||
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Author | Zhao, X.N.; Xu, W.; Xiao, Y.M.; Liu, J.; Van Duppen, B.; Peeters, F.M. | ||||
Title | Terahertz optical Hall effect in monolayer MoS₂ in the presence of proximity-induced interactions | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 24 | Pages | 245412-12 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | The effect of proximity-induced interactions such as Rashba spin-orbit coupling (SOC) and exchange interaction on the electronic and optical properties of n-type monolayer (ML) MoS2 is investigated. We predict and demonstrate that the Rashba SOC can induce an in-plane spin splitting with terahertz (THz) energy, while the exchange interaction lifts the energy degeneracy in different valleys. Thus, spin polarization can be achieved in an n-type ML MoS2 and valley Hall or optical Hall effect can be observed using linearly polarized THz radiation. In such a case, the transverse optical conductivity sigma(xy) (omega) results from spin-flip transition within spin-split conduction bands and from the fact that contributions from electrons with different spin orientations in different valleys can no longer be canceled out. Interestingly, we find that for fixed effective Zeeman field (or exchange interaction) the lowest spin-split conduction band in ML MoS2 can be tuned from one in the K valley to another one in the K' valley by varying the Rashba parameter lambda(R). Therefore, by changing lambda(R) we can turn the sign of the spin polarization and Im sigma(xy) (omega) from positive to negative. Moreover, we find that the dominant contribution of the selection rules to sigma(xx)(omega) is from electrons in the K valley and to sigma(xy) (omega) is from electrons in the K' valley. These important and interesting theoretical findings can be helpful to experimental observation of the optical Hall effect in valleytronic systems using linearly polarized THz radiation fields. | ||||
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Language | Wos | 000538715500011 | Publication Date | 2020-06-09 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 8 | Open Access | |
Notes | ; This work was supported by the National Natural Science Foundation of China (Grants No. U1930116, No. U1832153, and No. 11574319) and the Center of Science and Technology of Hefei Academy of Science (Grant No. 2016FXZY002). ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:170206 | Serial | 6622 | ||
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Author | Van der Donck, M.; Conti, S.; Perali, A.; Hamilton, A.R.; Partoens, B.; Peeters, F.M.; Neilson, D. | ||||
Title | Three-dimensional electron-hole superfluidity in a superlattice close to room temperature | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 6 | Pages | 060503 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Although there is strong theoretical and experimental evidence for electron-hole superfluidity in separated sheets of electrons and holes at low T, extending superfluidity to high T is limited by strong two-dimensional fluctuations and Kosterlitz-Thouless effects. We show this limitation can be overcome using a superlattice of alternating electron- and hole-doped semiconductor monolayers. The superfluid transition in a three-dimensional superlattice is not topological, and for strong electron-hole pair coupling, the transition temperature T-c can be at room temperature. As a quantitative illustration, we show T-c can reach 270 K for a superfluid in a realistic superlattice of transition metal dichalcogenide monolayers. | ||||
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Language | Wos | 000562320700001 | Publication Date | 2020-08-25 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 8 | Open Access | |
Notes | ; This work was supported by the Research Foundation of Flanders (FWO-Vl) through an aspirant research grant for M.V.d.D., by the FLAG-ERA project TRANS-2D-TMD, and by the Australian Government through the Australian Research Council Centre of Excellence in Future Low-Energy Electronics (Project No. CE170100039). We thank Milorad V. Milossevi ' c, Pierbiagio Pieri, and Jacques Tempere for helpful discussions. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:172064 | Serial | 6628 | ||
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Author | Leishman, A.W.D.; Menezes, R.M.; Longbons, G.; Bauer, E.D.; Janoschek, M.; Honecker, D.; DeBeer-Schmitt, L.; White, J.S.; Sokolova, A.; Milošević, M.V.; Eskildsen, M.R. | ||||
Title | Topological energy barrier for skyrmion lattice formation in MnSi | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 10 | Pages | 104416-104419 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | We report the direct measurement of the topological skyrmion energy barrier through a hysteresis of the skyrmion lattice in the chiral magnet MnSi. Measurements were made using small-angle neutron scattering with a custom-built resistive coil to allow for high-precision minor hysteresis loops. The experimental data were analyzed using an adapted Preisach model to quantify the energy barrier for skyrmion formation and corroborated by the minimum-energy path analysis based on atomistic spin simulations. We reveal that the skyrmion lattice in MnSi forms from the conical phase progressively in small domains, each of which consisting of hundreds of skyrmions, and with an activation barrier of several eV. | ||||
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Language | Wos | 000568994800005 | Publication Date | 2020-09-14 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 1 | Open Access | |
Notes | ; This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Award No. DE-SC0005051 (A.W.D.L., G.L., M.R.E.), the Research Foundation -Flanders (FWO-Vlaanderen) (R.M.M., M.V.M.), and Brazilian Agencies FACEPE, CAPES and CNPq (R.M.M.). M.J. was supported by the LANL Directed Research and Development (LDRD) program via the Directed Research (DR) project “A New Approach to Mesoscale Functionality: Emergent Tunable Superlattices (20150082DR).” E.D.B. was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under project “Quantum Fluctuations in Narrow-Band Systems.” A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Part of this work is based on experiments performed at the Swiss spallation neutron source SINQ, Paul Scherrer Institute, Villigen, Switzerland. We acknowledge useful conversations with E. Louden, D. Green, and A. Francisco in preparation for these experiments, as well as the assistance of K. Avers, G. Taufer, M. Harrington, M. Bartkowiak, and C. Baldwin in completing them. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:171959 | Serial | 6631 | ||
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Author | Bafekry, A.; Neek-Amal, M. | ||||
Title | Tuning the electronic properties of graphene-graphitic carbon nitride heterostructures and heterojunctions by using an electric field | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 8 | Pages | 085417-10 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Integration of graphene-based two-dimensional materials is essential for nanoelectronics applications. Using density-functional theory, we systematically investigate the electronic properties of vertically stacked graphene-graphitic carbon nitrides (GE/GCN). We also studied the covalently lateral stitched graphene-graphitic carbon nitrides (GE-GCN heterojunctions). The effects of perpendicular electric field on the electronic properties of six different heterostructures, i.e., (i) one layer of GE on top of a layer of CnNm with (n, m) = (3,1), (3,4), and (4,3) and (ii) three heterostructures CnNm/Cn'Nm', where (n, m) not equal (n', m') are elucidated. The most important calculated features are (i) the systems GE/C3N4, C3N/C3N4, GE-C3N, GE-C4N3, and C3N-C3N4 exhibit semiconducting characteristics having small band gaps of Delta(0)=20, 250, 100, 100, 80 meV, respectively while (ii) the systems GE/C4N3, C3N/C4N3, and C3N-C4N3 show ferromagnetic-metallic properties. In particular, we found that, in semiconducting heterostructures, the band gap increases nontrivially with increasing the absolute value of the applied perpendicular electric field. This work is useful for designing heterojunctions and heterostructures made of graphene and other two-dimensional materials such as those proposed in recent experiments [X. Liu and M. C. Hersam Sci. Adv. 5, 6444 (2019)]. | ||||
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Language | Wos | 000515659700007 | Publication Date | 2020-02-26 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 24 | Open Access | |
Notes | ; ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:167760 | Serial | 6640 | ||
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Author | Bafekry, A.; Neek-Amal, M.; Peeters, F.M. | ||||
Title | Two-dimensional graphitic carbon nitrides: strain-tunable ferromagnetic ordering | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 16 | Pages | 165407-165408 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Using first-principle calculations, we systematically study strain tuning of the electronic properties of two- dimensional graphitic carbon nitride nanosheets with empirical formula CnNm. We found the following: (i) the ferromagnetic ordered state in the metal-free systems (n, m) = (4,3), (10,9), and (14,12) remains stable in the presence of strain of about 6%. However, the system (9,7) loses its ferromagnetic ordering when increasing strain. This is due to the presence of topological defects in the (9,7) system, which eliminates the asymmetry between spin up and spin down of the p(z) orbitals when strain is applied. (ii) By applying uniaxial strain, a band gap opens in systems which are initially gapless. (iii) In semiconducting systems which have an initial gap of about 1 eV, the band gap is closed with applying uniaxial strain. | ||||
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Language | Wos | 000523630200012 | Publication Date | 2020-04-06 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 27 | Open Access | |
Notes | ; ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:168560 | Serial | 6643 | ||
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Author | Savchenko, T.M.; Buzzi, M.; Howald, L.; Ruta, S.; Vijayakumar, J.; Timm, M.; Bracher, D.; Saha, S.; Derlet, P.M.; Béché, A.; Verbeeck, J.; Chantrell, R.W.; Vaz, C.A.F.; Nolting, F.; Kleibert, A. | ||||
Title | Single femtosecond laser pulse excitation of individual cobalt nanoparticles | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 20 | Pages | 205418 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Laser-induced manipulation of magnetism at the nanoscale is a rapidly growing research topic with potential for applications in spintronics. In this work, we address the role of the scattering cross section, thermal effects, and laser fluence on the magnetic, structural, and chemical stability of individual magnetic nanoparticles excited by single femtosecond laser pulses. We find that the energy transfer from the fs laser pulse to the nanoparticles is limited by the Rayleigh scattering cross section, which in combination with the light absorption of the supporting substrate and protective layers determines the increase in the nanoparticle temperature. We investigate individual Co nanoparticles (8 to 20 nm in size) as a prototypical model system, using x-ray photoemission electron microscopy and scanning electron microscopy upon excitation with single femtosecond laser pulses of varying intensity and polarization. In agreement with calculations, we find no deterministic or stochastic reversal of the magnetization in the nanoparticles up to intensities where ultrafast demagnetization or all-optical switching is typically reported in thin films. Instead, at higher fluences, the laser pulse excitation leads to photo-chemical reactions of the nanoparticles with the protective layer, which results in an irreversible change in the magnetic properties. Based on our findings, we discuss the conditions required for achieving laser-induced switching in isolated nanomagnets. | ||||
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Language | Wos | 000589602000005 | Publication Date | 2020-11-16 | |
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ISSN | 2469-9950 | ISBN | Additional Links | UA library record; WoS full record | |
Impact Factor | 3.7 | Times cited | 1 | Open Access | OpenAccess |
Notes | This work received funding by the Swiss National Foundation (SNF) (Grants No. 200021160186 and No. 2002153540), the Swiss Nanoscience Institute (SNI) (Grant No. SNI P1502), the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 737093 (FEMTOTERABYTE), and the COST Action CA17123 (MAGNETOFON). Part of this work was performed at the SIM beamline of the Swiss Light Source (SLS), Paul Scherrer Institut, Villigen, Switzerland. Part of the simulations were undertaken on the VIKING cluster, which is a high-performance compute facility provided by the University of York. We kindly acknowledge Anja Weber from PSI for preparation of substrates with marker structures. A.B. and Jo Verbeeck acknowledge funding through FWO Project No. G093417N (“Compressed sensing enabling low dose imaging in transmission electron microscopy”) from the Flanders Research Fund. Jo Verbeeck acknowledges funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 823717 – ESTEEM3. S.S. acknowledges ETH Zurich Post-Doctoral fellowship and Marie Curie actions for people COFUND program.; esteem3JRA; esteem3reported | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | EMAT @ emat @c:irua:174273 | Serial | 6669 | ||
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Author | Milovanović, S.P.; Andelkovic, M.; Covaci, L.; Peeters, F.M. | ||||
Title | Band flattening in buckled monolayer graphene | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 24 | Pages | 245427 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) | ||||
Abstract | The strain fields of periodically buckled graphene induce a periodic pseudomagnetic field (PMF) that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudomagnetic field, we determine the necessary conditions to access the regime of correlated phases by examining the band flattening. As compared to twisted bilayer graphene the proposed system has the advantages that (1) only a single layer of graphene is needed, (2) one is not limited to hexagonal superlattices, and (3) narrower flat bandwidth and larger separation between flat bands can be induced. We, therefore, propose that periodically strained graphene single layers can become a platform for the exploration of exotic many-body phases. | ||||
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Language | Wos | 000602844600007 | Publication Date | 2020-12-28 | |
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ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 27 | Open Access | OpenAccess |
Notes | ; S.P.M. is supported by the Flemish Science Foundation (FWO). We thank E. Y. Andrei, Y. Jiang, and J. Mao for fruitful discussions. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:175021 | Serial | 6684 | ||
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Author | Shekarforoush, S.; Jalali, H.; Yagmurcukardes, M.; Milošević, M.V.; Neek-Amal, M. | ||||
Title | Optoelectronic properties of confined water in angstrom-scale slits | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 102 | Issue | 23 | Pages | 235406 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | The optoelectronic properties of confined water form one of the most active research areas in the past few years. Here we present the multiscale methodology to discern the out-of-plane electronic and dipolar dielectric constants (epsilon(el)(perpendicular to) and epsilon(diP)(perpendicular to)) of strongly confined water. We reveal that epsilon(perpendicular to el) and epsilon(diP)(perpendicular to) become comparable for water confined in angstrom-scale channels (with a height of less than 15 angstrom) within graphene (GE) and hexagonal boron nitride (hBN) bilayers. Channel height (h) associated with a minimum in both epsilon(e)(l)(perpendicular to) and epsilon(dip)(perpendicular to) is linked to the formation of the ordered structure of ice for h approximate to (7 -7.5) angstrom. The recently measured total dielectric constant epsilon(T)(perpendicular to) of nanoconfined water [L. Fumagalli et al., Science 360, 1339 (2018)] is corroborated by our results. Furthermore, we evaluate the contribution from the encapsulating membranes to the dielectric properties, as a function of the interlayer spacing, i.e., the height of the confining channel for water. Finally, we conduct analysis of the optical properties of both confined water and GE membranes, and show that the electron energy loss function of confined water strongly differs from that of bulk water. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000595856100004 | Publication Date | 2020-12-04 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | 1 | Open Access | |
Notes | ; This work was supported by the Research Foundation – Flanders (FWO). M.Y. gratefully acknowledges his FWO postdoctoral mandate. ; | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:175051 | Serial | 6695 | ||
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Author | Wozniak, T.; Faria, P.E., Jr.; Seifert, G.; Chaves, A.; Kunstmann, J. | ||||
Title | Exciton g factors of van der Waals heterostructures from first-principles calculations | Type | A1 Journal article | ||
Year | 2020 | Publication | Physical Review B | Abbreviated Journal | Phys Rev B |
Volume | 101 | Issue | 23 | Pages | 235408-235411 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | External fields are a powerful tool to probe optical excitations in a material. The linear energy shift of an excitation in a magnetic field is quantified by its effective g factor. Here we show how exciton g factors and their sign can be determined by converged first-principles calculations. We apply the method to monolayer excitons in semiconducting transition metal dichalcogenides and to interlayer excitons in MoSe2/WSe2 heterobilayers and obtain good agreement with recent experimental data. The precision of our method allows us to assign measured g factors of optical peaks to specific transitions in the band structure and also to specific regions of the samples. This revealed the nature of various, previously measured interlayer exciton peaks. We further show that, due to specific optical selection rules, g factors in van der Waals heterostructures are strongly spin and stacking-dependent. The calculation of orbital angular momenta requires the summation over hundreds of bands, indicating that for the considered two-dimensional materials the basis set size is a critical numerical issue. The presented approach can potentially be applied to a wide variety of semiconductors. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000537315100009 | Publication Date | 2020-06-03 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.7 | Times cited | Open Access | ||
Notes | Approved | Most recent IF: 3.7; 2020 IF: 3.836 | |||
Call Number | UA @ admin @ c:irua:170219 | Serial | 7944 | ||
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Author | Bercx, M.; Partoens, B.; Lamoen, D. | ||||
Title | Quantitative modeling of secondary electron emission from slow-ion bombardment on semiconductors | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 8 | Pages | 085413 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) | ||||
Abstract | When slow ions incident on a surface are neutralized, the excess potential energy is passed on to an electron inside the surface, leading to emission of secondary electrons. The microscopic description of this process, as well as the calculation of the secondary electron yield, is a challenging problem due to its complexity as well as its sensitivity to surface properties. One of the first quantitative descriptions was articulated in the 1950s by Hagstrum, who based his calculation on a parametrization of the density of states of the material. In this paper, we present a model for calculating the secondary electron yield, derived from Hagstrum’s initial approach. We use first-principles density functional theory calculations to acquire the necessary input and introduce the concept of electron cascades to Hagstrum’s model in order to improve the calculated spectra, as well as remove its reliance on fitting parameters. We apply our model to He+ and Ne+ ions incident on Ge(111) and Si(111) and obtain yield spectra that match closely to the experimental results of Hagstrum. |
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000458367800010 | Publication Date | 2019-02-11 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 5 | Open Access | OpenAccess |
Notes | We would like to thank Prof. D. Depla for the useful discussions on the secondary electron yield. Furthermore, we acknowledge financial support of FWO-Vlaanderen through project G.0216.14N. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the FWOVlaanderen and the Flemish Government-department EWI. | Approved | Most recent IF: 3.836 | ||
Call Number | EMAT @ emat @UA @ admin @ c:irua:157174 | Serial | 5154 | ||
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Author | Torre, I.; de Castro, L.V.; Van Duppen, B.; Barcons Ruiz, D.; Peeters, F.M.; Koppens, F.H.L.; Polini, M. | ||||
Title | Acoustic plasmons at the crossover between the collisionless and hydrodynamic regimes in two-dimensional electron liquids | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 14 | Pages | 144307 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Hydrodynamic flow in two-dimensional electron systems has so far been probed only by dc transport and scanning gate microscopy measurements. In this work we discuss theoretically signatures of the hydrodynamic regime in near-field optical microscopy. We analyze the dispersion of acoustic plasmon modes in two-dimensional electron liquids using a nonlocal conductivity that takes into account the effects of (momentumconserving) electron-electron collisions, (momentum-relaxing) electron-phonon and electron-impurity collisions, and many-body interactions beyond the celebrated random phase approximation. We derive the dispersion and, most importantly, the damping of acoustic plasmon modes and their coupling to a near-field probe, identifying key experimental signatures of the crossover between collisionless and hydrodynamic regimes. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000465160000003 | Publication Date | 2019-04-18 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 14 | Open Access | |
Notes | ; This work has been sponsored by the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 785219 “Graphene Core2” and via the European Research Council (ERC) Grant Agreement No. 786285. B.V.D. is supported by a post-doctoral fellowship of the Flemish Science Foundation (FWO-Vl). F.H.L.K. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness, through the “ Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0522), support by Fundacio Cellex Barcelona, Generalitat de Catalunya through the CERCA program, and the Mineco grant Plan Nacional (FIS2016-81044-P) and the Agency for Management of University and Research Grants (AGAUR) 2017 SGR 1656. F.M.P. and L.V.d.C. were supported by the Methusalem Program of the Flemish Government. We thank Niels Hesp and Hanan Hertzig Sheinfux for useful discussions. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:159333 | Serial | 5193 | ||
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Author | Aslani, Z.; Sisakht, E.T.; Fazileh, F.; Ghorbanfekr-Kalashami, H.; Peeters, F.M. | ||||
Title | Conductance fluctuations of monolayer GeSnH2$ in the topological phase using a low-energy effective tight-binding Hamiltonian | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 11 | Pages | 115421 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | An effective tight-binding (TB) Hamiltonian for monolayer GeSnH2 is constructed which has an inversion-asymmetric honeycomb structure. The low-energy band structure of our TB model agrees very well with previous ab initio calculations even under biaxial tensile strain. Our model predicts a phase transition at 7.5% biaxial tensile strain in agreement with DFT calculations. Upon 8.5% strain the system exhibits a band gap of 134 meV, suitable for room temperature applications. It is shown that an external applied magnetic field produces a special phase which is a combination of the quantum Hall (QH) and quantum spin Hall (QSH) phases; and at a critical magnetic field strength the QSH phase completely disappears. The topological nature of the phase transition is confirmed from: (1) the calculation of the Z(2) topological invariant, and (2) quantum transport properties of disordered GeSnH2 nanoribbons which allows us to determine the universality class of the conductance fluctuations. The application of an external applied magnetic field reduces the conductance fluctuations by a factor of root 2. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000461958900006 | Publication Date | 2019-03-15 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 3 | Open Access | |
Notes | ; This work was supported by the FLAG-ERA project TRANS-2D-TMD. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:158538 | Serial | 5199 | ||
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Author | Dharma-Wardana, M.W.C.; Neilson, D.; Peeters, F.M. | ||||
Title | Correlation functions in electron-electron and electron-hole double quantum wells : temperature, density, and barrier-width dependence | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 3 | Pages | 035303 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | The classical-map hypernetted-chain (CHNC) scheme, developed for treating fermion fluids at strong coupling and at finite temperatures, is applied to electron-electron and electron-hole double quantum wells. The pair-distribution functions and the local field factors needed in linear-response theory are determined for a range of temperatures, carrier densities, and barrier widths typical for experimental double-quantum-well systems in GaAs-GaAlAs. For electron-hole double quantum wells, a large enhancement in the pair-distribution functions is found for small carrier separations. The CHNC equations for electron-hole systems no longer hold at low densities where bound-state formation occurs. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000455163800004 | Publication Date | 2019-01-08 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 6 | Open Access | |
Notes | ; This work was partially supported by the Flemish Science Foundation (FWO-Vl). M.W.C.D.-W. acknowledges with thanks the hospitality and stimulating atmosphere of the Condensed Matter Theory group at the University of Antwerp. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:156734 | Serial | 5201 | ||
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Author | Menezes, R.M.; Mulkers, J.; de Souza Silva, C.C.; Milošević, M.V. | ||||
Title | Deflection of ferromagnetic and antiferromagnetic skyrmions at heterochiral interfaces | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 10 | Pages | 104409 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Devising magnetic nanostructures with spatially heterogeneous Dzyaloshinskii-Moriya interaction (DMI) is a promising pathway toward advanced confinement and control of magnetic skyrmions in potential devices. Here we discuss theoretically how a skyrmion interacts with a heterochiral interface using micromagnetic simulations and analytic arguments. We show that a heterochiral interface deflects the trajectory of ferromagnetic (FM) skyrmions, and that the extent of such deflection is tuned by the applied spin-polarized current and the difference in DMI across the interface. Further, we show that this deflection is characteristic of the FM skyrmion, and it is completely absent in the antiferromagnetic (AFM) case. In turn, we reveal that the AFM skyrmion achieves much higher velocities than its FM counterpart, yet experiences far stronger confinement in nanoengineered heterochiral tracks, which reinforces AFM skyrmions as a favorable choice for skyrmion-based devices. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000460720600005 | Publication Date | 2019-03-07 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 19 | Open Access | |
Notes | ; This work was supported by the Research Foundation-Flanders (FWO-Vlaanderen) and Brazilian Agencies FACEPE under Grant No. APQ-0198-1.05/14, CAPES and CNPq. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:158557 | Serial | 5203 | ||
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Author | Neek-Amal, M.; Rashidi, R.; Nair, R.R.; Neilson, D.; Peeters, F.M. | ||||
Title | Electric-field-induced emergent electrical connectivity in graphene oxide | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 11 | Pages | 115425 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Understanding the appearance of local electrical connectivity in liquid filled layered graphene oxide subjected to an external electric field is important to design electrically controlled smart permeable devices and also to gain insight into the physics behind electrical effects on confined water permeation. Motivated by recent experiments [K. G. Zhou et al. Nature (London) 559, 236 (2018)], we introduce a new model with random percolating paths for electrical connectivity in micron thick water filled layered graphene oxide, which mimics parallel resistors connected across the top and bottom electrodes. We find that a strong nonuniform radial electric field of the order similar to 10-50 mV/nm can be induced between layers depending on the current flow through the formed conducting paths. The maxima of the induced fields are not necessarily close to the electrodes and may be localized in the middle region of the layered material. The emergence of electrical connectivity and the associated electrical effects have a strong influence on the surrounding fluid in terms of ionization and wetting which subsequently determines the permeation properties. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000461960100001 | Publication Date | 2019-03-19 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 3 | Open Access | |
Notes | ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:158534 | Serial | 5206 | ||
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Author | Lozano, D.P.; Couet, S.; Petermann, C.; Hamoir, G.; Jochum, J.K.; Picot, T.; Menendez, E.; Houben, K.; Joly, V.; Antohe, V.A.; Hu, M.Y.; Leu, B.M.; Alatas, A.; Said, A.H.; Roelants, S.; Partoens, B.; Milošević, M.V.; Peeters, F.M.; Piraux, L.; Van de Vondel, J.; Vantomme, A.; Temst, K.; Van Bael, M.J. | ||||
Title | Experimental observation of electron-phonon coupling enhancement in Sn nanowires caused by phonon confinement effects | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 6 | Pages | 064512 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Reducing the size of a superconductor below its characteristic length scales can either enhance or suppress its critical temperature (T-c). Depending on the bulk value of the electron-phonon coupling strength, electronic and phonon confinement effects will play different roles in the modification of T-c. Experimentally disentangling each contribution has remained a challenge. We have measured both the phonon density of states and T-c of Sn nanowires with diameters of 18, 35, and 100 nm in order to quantify the effects of phonon confinement on superconductivity. We observe a shift of the phonon frequency towards the low-energy region and an increase in the electron-phonon coupling constant that can account for the measured increase in T-c. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000459322400005 | Publication Date | 2019-02-21 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 11 | Open Access | |
Notes | ; We would like to thanks Jeroen Scheerder and Wout Keijers for their help and assistance during the low-temperature measurements. This work was supported by the Research Foundation Flanders (FWO), the Concerted Research Action (GOA/14/ 007), the Federation Wallonie-Bruxelles (ARC 13/18-052, Supracryst) and the Fonds de la Recherche Scientifique -FNRS under Grant No. T.0006.16. The authors acknowledge Hercules Stichting (Project Nos. AKUL/13/19 and AKUL/13/25). D.P.L. thanks the FWO for financial support. This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:158621 | Serial | 5212 | ||
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Author | Wang, W.; Van Duppen, B.; Peeters, F.M. | ||||
Title | Intense-terahertz-laser-modulated magnetopolaron effect on shallow-donor states in the presence of magnetic field in the Voigt configuration | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 1 | Pages | 014114 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | The laser-modulated magnetopolaron effect on shallow donors in semiconductors is investigated in the presence of a magnetic field in the Voigt configuration. A nonperturbative approach is used to describe the electron-photon interaction by including the radiation field in an exact way via a laser-dressed interaction potential. Through a variational approach we evaluate the donor binding energy. We find that the interaction strength of the laser-dressed Coulomb potential in the z direction cannot only be enhanced but also weakened by the radiation field, while that in the x-y plane is only weakened. In this way, the binding energy of the states with odd z parity, like 2p(z) can be decreased or increased with respect to its static binding energy by the radiation field, while that of the other states can be only decreased. Furthermore, all binding energies become insensitive to the magnetic field if the radiation field is strong. The magnetopolaron effect on these energies is studied within second-order time-dependent perturbation theory. In the nonresonant region, a laser-modulated magnetopolaron correction, including the effect of single-photon processes, is observed. In the resonant region, a laser-modulated magnetopolaron effect, accompanied by the emission and absorption of a single photon, is found. Moreover, the 1s -> 2p(+) transition, accompanied by the emission of a single photon, is tuned by the radiation field into resonance with the longitudinal-optical phonon branch. This is electrically analogous to the magnetopolaron effect, and therefore we name it the dynamical magnetopolaron effect. Finally, by changing the frequency of the radiation field, these interesting effects can be tuned to be far away from the reststrahlen band and, therefore, can be detected experimentally. This in turn provides a direct measure of the electron-phonon interaction. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000457057500001 | Publication Date | 2019-01-29 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 7 | Open Access | |
Notes | ; This work was supported by National Natural Science Foundation of China (Grants No. 11404214, No. 11455015, and No. 61504016) and the China Scholarship Council (CSC), and Science and Technology Research Foundation of Jiangxi Provincial Education Department (Grants No. GJJ161062 and No. GJJ180868). B.V.D. was supported by the Research Foundation – Flanders (FWO-Vl) through a postdoctoral fellowship. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:157555 | Serial | 5218 | ||
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Author | Conti, S.; Perali, A.; Peeters, F.M.; Neilson, D. | ||||
Title | Multicomponent screening and superfluidity in gapped electron-hole double bilayer graphene with realistic bands | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 14 | Pages | 144517 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Superfluidity has recently been reported in double electron-hole bilayer graphene. The multiband nature of the bilayers is important because of the very small band gaps between conduction and valence bands. The long-range nature of the superfluid pairing interaction means that screening must be fully taken into account. We have carried out a systematic mean-field investigation that includes (i) contributions to screening from both intraband and interband excitations, (ii) the low-energy band structure of bilayer graphene with its small band gap and flattened Mexican-hat-like low-energy bands, (iii) the large density of states at the bottom of the bands, (iv) electron-hole pairing in the multibands, and (v) electron-hole pair transfers between the conduction and valence band condensates. We find that the superfluidity strongly modifies the intraband contributions to the screening, but that the interband contributions are unaffected. Unexpectedly, a net effect of the screening is to suppress Josephson-like pair transfers and to confine the superfluid pairing entirely to the conduction-band condensate even for very small band gaps, making the system behave similarly to a one-band superfluid. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000465160000004 | Publication Date | 2019-04-18 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 15 | Open Access | |
Notes | ; This work was partially supported by the Fonds Wetenschappelijk Onderzoek (FWO-Vl) and the Methusalem Foundation. We thank Mohammad Zarenia and Alfredo VargasParedes for useful discussions. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:159332 | Serial | 5221 | ||
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Author | Scuracchio, P.; Michel, K.H.; Peeters, F.M. | ||||
Title | Phonon hydrodynamics, thermal conductivity, and second sound in two-dimensional crystals | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 14 | Pages | 144303 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Starting from our previous work in which we obtained a system of coupled integrodifferential equations for acoustic sound waves and phonon density fluctuations in two-dimensional (2D) crystals, we derive here the corresponding hydrodynamic equations, and we study their consequences as a function of temperature and frequency. These phenomena encompass propagation and damping of acoustic sound waves, diffusive heat conduction, second sound, and Poiseuille heat flow, all of which are characterized by specific transport coefficients. We calculate these coefficients by means of correlation functions without using the concept of relaxation time. Numerical calculations are performed as well in order to show the temperature dependence of the transport coefficients and of the thermal conductivity. As a consequence of thermal tension, mechanical and thermal phenomena are coupled. We calculate the dynamic susceptibilities for displacement and temperature fluctuations and study their resonances. Due to the thermomechanical coupling, the thermal resonances such as the Landau-Placzek peak and the second-sound doublet appear in the displacement susceptibility, and conversely the acoustic sound wave doublet appears in the temperature susceptibility, Our analytical results not only apply to graphene, but they are also valid for arbitrary 2D crystals with hexagonal symmetry, such as 2D hexagonal boron nitride, 2H-transition-metal dichalcogenides, and oxides. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000464717300006 | Publication Date | 2019-04-10 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 16 | Open Access | |
Notes | ; This work was supported by the Flemish Science Foundation (FWO-Vl). ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:159346 | Serial | 5225 | ||
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Author | Yagmurcukardes, M.; Ozen, S.; Iyikanat, F.; Peeters, F.M.; Sahin, H. | ||||
Title | Raman fingerprint of stacking order in HfS2-Ca(OH)(2) heterobilayer | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 20 | Pages | 205405 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Using density functional theory-based first-principles calculations, we investigate the stacking order dependence of the electronic and vibrational properties of HfS2-Ca(OH)(2) heterobilayer structures. It is shown that while the different stacking types exhibit similar electronic and optical properties, they are distinguishable from each other in terms of their vibrational properties. Our findings on the vibrational properties are the following: (i) from the interlayer shear (SM) and layer breathing (LBM) modes we are able to deduce the AB' stacking order, (ii) in addition, the AB' stacking type can also be identified via the phonon softening of E-g(I) and A(g)(III) modes which harden in the other two stacking types, and (iii) importantly, the ultrahigh frequency regime possesses distinctive properties from which we can distinguish between all stacking types. Moreover, the differences in optical and vibrational properties of various stacking types are driven by two physical effects, induced biaxial strain on the layers and the layer-layer interaction. Our results reveal that with both the phonon frequencies and corresponding activities, the Raman spectrum possesses distinctive properties for monitoring the stacking type in novel vertical heterostructures constructed by alkaline-earth-metal hydroxides. | ||||
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Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Wos | 000467387800010 | Publication Date | 2019-05-06 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 27 | Open Access | |
Notes | ; Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). H.S. acknowledges financial support from the Scientific and Technological Research Council of Turkey (TUBITAK) under the Project No. 117F095. H.S. acknowledges support from Turkish Academy of Sciences under the GEBIP program. This work is supported by the Flemish Science Foundation (FWO-Vl) by a postdoctoral fellowship (M.Y.). ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:160334 | Serial | 5226 | ||
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Author | Van der Donck, M.; Peeters, F.M. | ||||
Title | Spectrum of exciton states in monolayer transition metal dichalcogenides : angular momentum and Landau levels | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 11 | Pages | 115439 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | A four-band exciton Hamiltonian is constructed starting from the single-particle Dirac Hamiltonian for charge carriers in monolayer transition metal dichalcogenides (TMDs). The angular part of the exciton wave function can be separated from the radial part, in the case of zero center of mass momentum excitons, by exploiting the eigenstates of the total exciton angular momentum operator with which the Hamiltonian commutes. We explain why this approach fails for excitons with finite center of mass momentum or in the presence of a perpendicular magnetic field and present an approximation to resolve this issue. We calculate the (binding) energy and average interparticle distance of different excited exciton states in different TMDs and compare these with results available in the literature. Remarkably, we find that the intervalley exciton ground state in the -/+ K valley has angular momentum j = +/- 1, which is due to the pseudospin of the separate particles. The exciton mass and the exciton Landau levels are calculated and we find that the degeneracy of exciton states with opposite relative angular momentum is altered by a magnetic field. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000462896400004 | Publication Date | 2019-03-28 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 10 | Open Access | |
Notes | ; This work was supported by the Research Foundation of Flanders (FWO-Vl) through an aspirant research grant for MVDD and by the FLAG-ERA project TRANS-2D-TMD. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:159406 | Serial | 5230 | ||
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Author | Van Pottelberge, R.; Peeters, F.M. | ||||
Title | Tunable circular dipolelike system in graphene : mixed electron-hole states | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 12 | Pages | 125426 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | Coupled electron-hole states are realized in a system consisting of a combination of an electrostatic potential barrier and ring-shaped potential well, which resembles a circular dipole. A perpendicular magnetic field induces confined states inside the Landau gaps which are mainly located at the barrier or ring. Hybridizations between the barrier and ring states are seen as anticrossings in the energy spectrum. As a consequence, the energy levels show an oscillating dependence on the electrostatic potential strength in combination with an oscillating migration of the wave functions between the barrier and ring. At the anticrossing points the quantum state consists of a mixture of electron and hole. The present system mimics closely the behavior of a relativistic dipole on gapped graphene. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000462900200005 | Publication Date | 2019-03-27 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 4 | Open Access | |
Notes | ; We thank M. 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. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:159409 | Serial | 5237 | ||
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Author | Behera, B.C.; Jana, S.; Bhat, S.G.; Gauquelin, N.; Tripathy, G.; Kumar, P.S.A.; Samal, D. | ||||
Title | Evidence for exchange bias coupling at the perovskite/brownmillerite interface in spontaneously stabilized SrCoO3-\delta/SrCoO2.5 bilayers | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 2 | Pages | 024425 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Interface effect in complex oxide thin-film heterostructures lies at the vanguard of current research to design technologically relevant functionality and explore emergent physical phenomena. While most of the previous works focus on the perovskite/perovskite heterostructures, the study of perovskite/brownmillerite interfaces remains in its infancy. Here, we investigate spontaneously stabilized perovskite-ferromagnet (SrCoO3-delta)/brownmillerite-antiferromagnet (SrCoO2.5) bilayer with T-N > T-C and discover an unconventional interfacial magnetic exchange bias effect. From magnetometry investigations, it is rationalized that the observed effect stems from the interfacial ferromagnet/antiferromagnet coupling. The possibility for coupled ferromagnet/spin-glass interface engendering such effect is ruled out. Strikingly, a finite coercive field persists in the paramagnetic state of SrCoO3-delta,whereas the exchange bias field vanishes at T-C . We conjecture the observed effect to be due to the effective external quenched staggered field provided by the antiferromagnetic layer for the ferromagnetic spins at the interface. Our results not only unveil a paradigm to tailor the interfacial magnetic properties in oxide heterostructures without altering the cations at the interface, but also provide a purview to delve into the fundamental aspects of exchange bias in such unusual systems, paving a big step forward in thin-film magnetism. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000456481900003 | Publication Date | 2019-01-23 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 2 | Open Access | OpenAccess |
Notes | ; We are grateful to Sachin Sarangi for his superb technical support during magnetic measurements. We thank Gopal Pradhan for fruitful discussion. We thank Zhicheng Zhong for reading the manuscript and for suggestions. We thank T. Som for extending laboratory facility. D.S. and B.C.B. acknowledge the financial support from Max-Planck Society through Max Planck Partner Group. S.G.B. acknowledges the INSPIRE Faculty Fellowship Programme (DSTO1899) for the financial support. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:157562 | Serial | 5248 | ||
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Author | Das, S.; Rata, A.D.; Maznichenko, I., V; Agrestini, I.S.; Pippel, E.; Gauquelin, N.; Verbeeck, J.; Chen, K.; Valvidares, S.M.; Vasili, H.B.; Herrero-Martin, J.; Pellegrin, E.; Nenkov, K.; Herklotz, A.; Ernst, A.; Mertig, I.; Hu, Z.; Doerr, K. | ||||
Title | Low-field switching of noncollinear spin texture at La0.7Sr0.3MnO3-SrRuO3interfaces | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 99 | Issue | 2 | Pages | 024416 |
Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
Abstract | Interfaces of ferroic oxides can show complex magnetic textures which have strong impact on spintronics devices. This has been demonstrated recently for interfaces with insulating antiferromagnets such as BiFeO3. Here, noncollinear spin textures which can be switched in very low magnetic field are reported for conducting ferromagnetic bilayers of La0.7Sr0.3MnO3-SrRuO3 (LSMO-SRO). The magnetic order and switching are fundamentally different for bilayers coherently grown in reversed stacking sequence. The SRO top layer forms a persistent exchange spring which is antiferromagnetically coupled to LSMO and drives switching in low fields of a few milliteslas. Density functional theory reveals the crucial impact of the interface termination on the strength of Mn-Ru exchange coupling across the interface. The observation of an exchange spring agrees with ultrastrong coupling for the MnO2/SrO termination. Our results demonstrate low-field switching of noncollinear spin textures at an interface between conducting oxides, opening a pathway for manipulating and utilizing electron transport phenomena in controlled spin textures at oxide interfaces. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000455821400005 | Publication Date | 2019-01-15 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 19 | Open Access | OpenAccess |
Notes | ; The research in Halle was supported by Deutsche Forschungsgemeinschaft (DFG), SFB 762 Functional Oxide Interfaces (Projects No. A9 and No. B1). K.C. benefited from support of the DFG (Project 600575). Discussions with M. Trassin, M. Ziese, H. M. Christen, E.-J. Guo, F. Grcondciel, M. Bibes, and H. N. Lee are gratefully acknowledged. N. G. and J. V. acknowledge funding under the GOA project “Solarpaint” of the University of Antwerp. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:156717 | Serial | 5255 | ||
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Author | Sabzalipour, A.; Partoens, B. | ||||
Title | Anomalous Hall effect in magnetic topological insulators : semiclassical framework | Type | A1 Journal article | ||
Year | 2019 | Publication | Physical review B | Abbreviated Journal | Phys Rev B |
Volume | 100 | Issue | 3 | Pages | 035419 |
Keywords | A1 Journal article; Condensed Matter Theory (CMT) | ||||
Abstract | The anomalous Hall effect (AHE) is studied on the surface of a 3D magnetic topological insulator. By applying a modified semiclassical framework, all three contributions to the AHE, the Berry curvature effect, the side jump effect and the skew scattering effects are systematically treated, and analytical expressions for the conductivities are obtained in terms of the Fermi level, the spatial orientation of the surface magnetization and the concentration of magnetic and nonmagnetic impurities. We demonstrate that the AHE can change sign by altering the orientation of the surface magnetization, the concentration of the impurities and also the position of the Fermi level, in agreement with recent experimental observations. We show how each contribution to the AHE, or even the whole AHE, can be turned off by properly adjusting the given parameters. For example, one can turn off the anomalous hall conductivity in a system with in-plane magnetization by pushing the system into the fully metallic regime. | ||||
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Publisher | Place of Publication | Editor | |||
Language | Wos | 000475499200007 | Publication Date | 2019-07-15 | |
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 2469-9969; 2469-9950 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
Impact Factor | 3.836 | Times cited | 2 | Open Access | |
Notes | ; ; | Approved | Most recent IF: 3.836 | ||
Call Number | UA @ admin @ c:irua:161219 | Serial | 5406 | ||
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