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Author Bercx, M.; Partoens, B.; Lamoen, D. pdf  url
doi  openurl
  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 (up) 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.
 
  Address  
  Corporate Author Thesis  
  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  
Permanent link to this record
 

 
Author Torre, I.; de Castro, L.V.; Van Duppen, B.; Barcons Ruiz, D.; Peeters, F.M.; Koppens, F.H.L.; Polini, M. url  doi
openurl 
  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 (up) 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.  
  Address  
  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 10 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 Saberi-Pouya, S.; Zarenia, M.; Vazifehshenas, T.; Peeters, F.M. url  doi
openurl 
  Title Anisotropic charge density wave in electron-hole double monolayers : applied to phosphorene Type A1 Journal article
  Year 2018 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 98 Issue 24 Pages 245115  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The possibility of an inhomogeneous charge density wave phase is investigated in a system of two coupled electron and hole monolayers separated by a hexagonal boron nitride insulating layer. The charge-density-wave state is induced through the assumption of negative compressibility of electron/hole gases in a Coulomb drag configuration between the electron and hole sheets. Under equilibrium conditions, we derive analytical expressions for the density oscillation along the zigzag and armchair directions. We find that the density modulation not only depends on the sign of the compressibility but also on the anisotropy of the low-energy bands. Our results are applicable to any two-dimensional system with anisotropic parabolic bands, characterized by different effective masses. For equal effective masses, i.e., isotropic energy bands, our results agree with Hroblak et al. [Phys. Rev. B 96, 075422 (2017)]. Our numerical results are applied to phosphorene.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000452995600001 Publication Date 2018-12-12  
  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  
  Impact Factor 3.836 Times cited Open Access  
  Notes ; This work was partially supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program of the Flemish government and Iran Science Elites Federation. ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:156233 Serial 5195  
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Author Aslani, Z.; Sisakht, E.T.; Fazileh, F.; Ghorbanfekr-Kalashami, H.; Peeters, F.M. url  doi
openurl 
  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 (up) 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.  
  Address  
  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 2 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. url  doi
openurl 
  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 (up) 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.  
  Address  
  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. url  doi
openurl 
  Title Deflection of ferromagnetic and antiferromagnetic skyrmions at heterochiral interfaces Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  Corporate Author Thesis  
  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. url  doi
openurl 
  Title Electric-field-induced emergent electrical connectivity in graphene oxide Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  Corporate Author Thesis  
  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 Van der Donck, M.; Peeters, F.M. url  doi
openurl 
  Title Excitonic complexes in anisotropic atomically thin two-dimensional materials : black phosphorus and TiS3 Type A1 Journal article
  Year 2018 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 98 Issue 23 Pages 235401  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The effect of anisotropy in the energy spectrum on the binding energy and structural properties of excitons, trions, and biexcitons is investigated. To this end we employ the stochastic variational method with a correlated Gaussian basis. We present results for the binding energy of different excitonic complexes in black phosphorus (bP) and TiS3 and compare them with recent results in the literature when available, for which we find good agreement. The binding energies of excitonic complexes in bP are larger than those in TiS3. We calculate the different average interparticle distances in bP and TiS3 and show that excitonic complexes in bP are strongly anisotropic whereas in TiS3 they are almost isotropic, even though the constituent particles have an anisotropic energy spectrum. This is also confirmed by the correlation functions.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000452003400009 Publication Date 2018-12-03  
  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 3.836 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:156247 Serial 5211  
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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. url  doi
openurl 
  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 (up) 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.  
  Address  
  Corporate Author Thesis  
  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 8 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. url  doi
openurl 
  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 (up) 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.  
  Address  
  Corporate Author Thesis  
  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 6 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. url  doi
openurl 
  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 (up) 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.  
  Address  
  Corporate Author Thesis  
  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 13 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. doi  openurl
  Title Phonon hydrodynamics, thermal conductivity, and second sound in two-dimensional crystals Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  Corporate Author Thesis  
  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 13 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. url  doi
openurl 
  Title Raman fingerprint of stacking order in HfS2-Ca(OH)(2) heterobilayer Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  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 23 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. url  doi
openurl 
  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 (up) 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.  
  Address  
  Corporate Author Thesis  
  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 9 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. url  doi
openurl 
  Title Tunable circular dipolelike system in graphene : mixed electron-hole states Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  Corporate Author Thesis  
  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 3 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 Sabzalipour, A.; Partoens, B. url  doi
openurl 
  Title Anomalous Hall effect in magnetic topological insulators : semiclassical framework Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) 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.  
  Address  
  Corporate Author Thesis  
  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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Author Topalovic, D.B.; Arsoski, V.V.; Tadic, M.Z.; Peeters, F.M. url  doi
openurl 
  Title Confined electron states in two-dimensional HgTe in magnetic field : quantum dot versus quantum ring behavior Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 12 Pages 125304  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract We investigate the electron states and optical absorption in square- and hexagonal-shaped two-dimensional (2D) HgTe quantum dots and quantum rings in the presence of a perpendicular magnetic field. The electronic structure is modeled by means of the sp(3)d(5)s* tight-binding method within the nearest-neighbor approximation. Both bulklike and edge states appear in the energy spectrum. The bulklike states in quantum rings exhibit Aharonov-Bohm oscillations in magnetic field, whereas no such oscillations are found in quantum dots, which is ascribed to the different topology of the two systems. When magnetic field varies, all the edge states in square quantum dots appear as quasibands composed of almost fully flat levels, whereas some edge states in quantum rings are found to oscillate with magnetic field. However, the edge states in hexagonal quantum dots are localized like in rings. The absorption spectra of all the structures consist of numerous absorption lines, which substantially overlap even for small line broadening. The absorption lines in the infrared are found to originate from transitions between edge states. It is shown that the magnetic field can be used to efficiently tune the optical absorption of HgTe 2D quantum dot and quantum ring systems.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000486638400007 Publication Date 2019-09-16  
  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 Projects No. III 41028, No. III 42008, and No. III 45003 funded by the Serbian Ministry of Education, Science and Technological Development, and the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:162787 Serial 5409  
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Author Abdullah, H.M.; da Costa, D.R.; Bahlouli, H.; Chaves, A.; Peeters, F.M.; Van Duppen, B. url  doi
openurl 
  Title Electron collimation at van der Waals domain walls in bilayer graphene Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 4 Pages 045137  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract We show that a domain wall separating single-layer graphene and AA-stacked bilayer graphene (AA-BLG) can be used to generate highly collimated electron beams which can be steered by a magnetic field. Two distinct configurations are studied, namely, locally delaminated AA-BLG and terminated AA-BLG whose terminal edge types are assumed to be either zigzag or armchair. We investigate the electron scattering using semiclassical dynamics and verify the results independently with wave-packet dynamics simulations. We find that the proposed system supports two distinct types of collimated beams that correspond to the lower and upper cones in AA-BLG. Our computational results also reveal that collimation is robust against the number of layers connected to AA-BLG and terminal edges.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000477892800005 Publication Date 2019-07-29  
  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 10 Open Access  
  Notes ; H.M.A. and H.B. acknowledge the support of King Fahd University of Petroleum and Minerals under research group Project No. RG181001. D.R.C and A.C. were financially supported by the Brazilian Council for Research (CNPq) and CAPES foundation. B.V.D. is supported by a postdoctoral fellowship by the Research Foundation Flanders (FWO-Vl). ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:161887 Serial 5410  
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Author Yagmurcukardes, M.; Sevik, C.; Peeters, F.M. url  doi
openurl 
  Title Electronic, vibrational, elastic, and piezoelectric properties of monolayer Janus MoSTe phases: A first-principles study Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 4 Pages 045415  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract By performing density functional theory based first-principles calculations, the electronic, vibrational, elastic, and piezoelectric properties of two dynamically stable crystal phases of monolayer Janus MoSTe, namely 1H-MoSTe and 1T'-MoSTe, are investigated. Vibrational frequency analysis reveals that the other possible crystal structure, 1T-MoSTe, of this Janus monolayer does not exhibit dynamical stability. The 1H-MoSTe phase is found to be an indirect band-gap semiconductor while 1T'-MoSTe is predicted as small-gap semiconductor. Notably, in contrast to the direct band-gap nature of monolayers 1H-MoS2 and 1H-MoTe2, 1H-MoSTe is found to be an indirect gap semiconductor driven by the induced surface strains on each side of the structure. The calculated Raman spectrum of each structure shows unique character enabling us to clearly distinguish the stable crystal phases via Raman measurements. The systematic piezoelectric stress and strain coefficient analysis reveals that out-of-plane piezoelectricity appears in 1H-MoSTe and the noncentral symmetric 1T'-MoSTe has large piezoelectric coefficients. Static total-energy calculations show clearly that the formation of 1T'-MoSTe is feasible by using 1T'-MoTe2 as a basis monolayer. Therefore, we propose that the Janus MoSTe structure can be fabricated in two dynamically stable phases which possess unique electronic, dynamical, and piezoelectric properties.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000476687800003 Publication Date 2019-07-19  
  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 91 Open Access  
  Notes ; Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). This work was 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:161899 Serial 5411  
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Author Houben, K.; Jochum, J.K.; Lozano, D.P.; Bisht, M.; Menendez, E.; Merkel, D.G.; Ruffer, R.; Chumakov, A., I; Roelants, S.; Partoens, B.; Milošević, M.V.; Peeters, F.M.; Couet, S.; Vantomme, A.; Temst, K.; Van Bael, M.J. url  doi
openurl 
  Title In situ study of the \alpha-Sn to \beta-Sn phase transition in low-dimensional systems : phonon behavior and thermodynamic properties Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 7 Pages 075408  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The densities of phonon states of thin Sn films on InSb substrates are determined during different stages of the alpha-Sn to beta-Sn phase transition using nuclear inelastic x-ray scattering. The vibrational entropy and internal energy per atom as a function of temperature are obtained by numerical integration of the phonon density of states. The free energy as a function of temperature for the nanoscale samples is compared to the free energy obtained from ab initio calculations of bulk tin in the alpha-Sn and beta-Sn phase. In thin films this phase transition is governed by the interplay between the vibrational behavior of the film (the phase transition is driven by the vibrational entropy) and the stabilizing influence of the substrate (which depends on the film thickness). This brings a deeper understanding of the role of lattice vibrations in the phase transition of nanoscale Sn.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000478992800005 Publication Date 2019-08-08  
  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 8 Open Access  
  Notes ; This work was supported by the Research Foundation Flanders (FWO) and the Concerted Research Action (Grant No. GOA14/007). K.H., S.C., D.P.L., and E.M. wish to thank the FWO for financial support. The authors gratefully acknowledge the European Synchrotron Radiation Facility (ESRF) for the granted beam time and the use of the in situ UHV preparation chamber. The authors thank B. Opperdoes for technical support and T. Peissker and R. Lieten for fruitful discussions. ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:161836 Serial 5416  
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Author Menezes, R.M.; Neto, J.F.S.; de Souza Silva, C.C.; Milošević, M.V. url  doi
openurl 
  Title Manipulation of magnetic skyrmions by superconducting vortices in ferromagnet-superconductor heterostructures Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 1 Pages 014431  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract Dynamics of magnetic skyrmions in hybrid ferromagnetic films harbors interesting physical phenomena and holds promise for technological applications. In this work, we discuss the behavior of magnetic skyrmions when coupled to superconducting vortices in a ferromagnet-superconductor heterostructure. We use numerical simulations and analytic arguments within London and Thiele formalisms to reveal broader possibilities for manipulating the skyrmion-vortex dynamic correlations in the hybrid system, that are not possible in its separated constituents. We explore the thresholds of particular dynamic phases, and quantify the phase diagram as a function of the relevant material parameters, applied current, and induced magnetic torques. Finally, we demonstrate the broad and precise tunability of the skyrmion Hall angle in the presence of vortices, with respect to currents applied to either or both the superconductor and the ferromagnet within the heterostructure.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000477883500004 Publication Date 2019-07-29  
  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 17 Open Access  
  Notes ; This work was supported by the Research Foundation – Flanders (FWO-Vlaanderen) and Brazilian Agencies Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, under Grant No. APQ-0198-1.05/14), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq). ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:161890 Serial 5421  
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Author Yagmurcukardes, M. url  doi
openurl 
  Title Monolayer fluoro-InSe : formation of a thin monolayer via fluorination of InSe Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 100 Issue 2 Pages 024108  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract By performing density functional theory-based first-principles calculations, the formation of a thin monolayer structure, namely InSeF, via fluorination of monolayer InSe is predicted. It is shown that strong interaction of F and In atoms leads to the detachment of In-Se layers in monolayer InSe and 1T-like monolayer InSeF structure is formed. Monolayer InSeF is found to be dynamically stable in terms of its phonon band dispersions. In addition, its Raman spectrum is shown to exhibit totally distinctive features as compared to monolayer InSe. The electronic band dispersions reveal that monolayer InSeF is a direct gap semiconductor whose valence and conduction band edges reside at the Gamma point. Moreover, the orientation-dependent linear elastic properties of monolayer InSeF are investigated in terms of the in-plane stiffness and Poisson ratio. It is found that monolayer InSeF displays strong in-plane anisotropy in elastic constants and it is slightly softer material as compared to monolayer InSe. Overall, it is proposed that a thin, direct gap semiconducting monolayer InSeF can be formed by full fluorination of monolayer InSe as a new member of the two-dimensional family.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000477885700003 Publication Date 2019-07-29  
  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 9 Open Access  
  Notes ; Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). 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:161891 Serial 5423  
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Author Yuan, H.F.; Xu, W.; Zhao, X.N.; Song, D.; Zhang, G.R.; Xiao, Y.M.; Ding, L.; Peeters, F.M. url  doi
openurl 
  Title Quantum and transport mobilities of a Na3Bi-based three-dimensional Dirac system Type A1 Journal article
  Year 2019 Publication Physical review B Abbreviated Journal (up) Phys Rev B  
  Volume 99 Issue 23 Pages 235303  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The electronic and transport properties of a three-dimensional (3D) Dirac system are investigated theoretically, which is motivated by recent experimental measurements on quantum and transport mobilities in the 3D Dirac semimetal Na3Bi by J. Xiong et al. [Science 350, 413 (2015); Europhys. Lett. 114, 27002 (2016)]. The electron Hamiltonian is taken from a simplified k center dot p approach. From the obtained electronic band structure and the Fermi energy, we explain why the anomalous effect induced by the chiral anomaly and the Berry curvature in the energy band can be observed experimentally in magnetotransport coefficients in both low-and high-density samples. Moreover, the quantum and transport mobilities are calculated on the basis of the momentum-balance equation derived from a semiclassical Boltzmann equation with the electron-impurity interaction. The quantum and transport mobilities obtained from this study agree both qualitatively and quantitatively with those measured experimentally. We also examine the electron mobilities along different crystal directions in Na3Bi and find them largely anisotropic. The theoretical findings from this work can be helpful in gaining an in-depth understanding of the experimental results and of the basic electronic and transport properties of newly developed 3D Dirac systems.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000471983500006 Publication Date 2019-06-17  
  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 1 Open Access  
  Notes ; ; Approved Most recent IF: 3.836  
  Call Number UA @ admin @ c:irua:161329 Serial 5425  
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Author Sabani, D.; Bacaksiz, C.; Milošević, M.V. url  doi
openurl 
  Title Ab initio methodology for magnetic exchange parameters: Generic four-state energy mapping onto a Heisenberg spin Hamiltonian Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 102 Issue 1 Pages 014457-14458  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The recent development in the field of two-dimensional magnetic materials urges reliable theoretical methodology for determination of magnetic properties. Among the available methods, ab initio four-state energy mapping based on density functional theory stands out as a powerful technique to calculate the magnetic exchange interaction in the Heisenberg spin model. Although the required formulas were explained in earlier works, the considered Hamiltonian in those studies always corresponded to the specific case that the off-diagonal part of J matrix is antisymmetric, which may be misleading in other cases. Therefore, using the most general form of the Heisenberg spin Hamiltonian, we here derive the generic formulas. With a proper choice of four different magnetic states, a single formula governs all elements of the exchange interaction matrix for any considered pair of spin sites.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000554409500002 Publication Date 2020-07-31  
  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 13 Open Access  
  Notes ; This work was supported by the Research Foundation-Flanders (FWO-Vlaanderen) and the Special Research Funds of the University of Antwerp (TOPBOF). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation-Flanders (FWO-Vlaanderen) and the Flemish Government, Department EWI. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:171203 Serial 6448  
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Author Devolder, T.; Bultynck, O.; Bouquin, P.; Nguyen, V.D.; Rao, S.; Wan, D.; Sorée, B.; Radu, I.P.; Kar, G.S.; Couet, S. url  doi
openurl 
  Title Back hopping in spin transfer torque switching of perpendicularly magnetized tunnel junctions Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 102 Issue 18 Pages 184406  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract We analyze the phenomenon of back hopping in spin-torque induced switching of the magnetization in perpendicularly magnetized tunnel junctions. The analysis is based on single-shot time-resolved conductance measurements of the pulse-induced back hopping. Studying several material variants reveals that the back hopping is a feature of the nominally fixed system of the tunnel junction. The back hopping is found to proceed by two sequential switching events that lead to a final state P' of conductance close to-but distinct from-that of the conventional parallel state. The P' state does not exist at remanence. It generally relaxes to the conventional antiparallel state if the current is removed. The P' state involves a switching of the sole spin-polarizing part of the fixed layers. The analysis of literature indicates that back hopping occurs only when the spin-polarizing layer is too weakly coupled to the rest of the fixed system, which justifies a posteriori the mitigation strategies of back hopping that were implemented empirically in spin-transfer-torque magnetic random access memories.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000587594900005 Publication Date 2020-11-09  
  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 ; This work was supported in part by the IMEC's Industrial Affiliation Program on STT-MRAM device, and in part by the imec IIAP core CMOS and the Beyond CMOS program of Intel Corporation. T. D. and P. B. thank Jonathan Z. Sun for constructive discussions on the BH phenomenon. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:173524 Serial 6458  
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Author Mirzakhani, M.; Peeters, F.M.; Zarenia, M. url  doi
openurl 
  Title Circular quantum dots in twisted bilayer graphene Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 101 Issue 7 Pages 075413  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract Within a tight-binding approach, we investigate the effect of twisting angle on the energy levels of circular bilayer graphene (BLG) quantum dots (QDs) in both the absence and presence of a perpendicular magnetic field. The QDs are defined by an infinite-mass potential, so that the specific edge effects are not present. In the absence of magnetic field (or when the magnetic length is larger than the moire length), we show that the low-energy states in twisted BLG QDs are completely affected by the formation of moire patterns, with a strong localization at AA-stacked regions. When magnetic field increases, the energy gap of an untwisted BLG QD closes with the edge states, localized at the boundaries between the AA- and AB-stacked spots in a twisted BLG QD. Our observation of the spatial localization of the electrons in twisted BLG QDs can be experimentally probed by low-bias scanning tunneling microscopy measurements.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000512772200004 Publication Date 2020-02-13  
  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 13 Open Access  
  Notes ; We gratefully acknowledge discussions with I. Snyman. M.Z. acknowledges support from the U.S. Department of Energy (Office of Science) under Grant No. DE-FG0205ER46203. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:166493 Serial 6470  
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Author Van Pottelberge, R. url  doi
openurl 
  Title Comment on “Electron states for gapped pseudospin-1 fermions in the field of a charged impurity” Type Editorial
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 101 Issue 19 Pages 197102-197103  
  Keywords Editorial; Condensed Matter Theory (CMT)  
  Abstract In a recent paper [Phys. Rev. B 99, 155124 (2019)], the spectrum of a regularized Coulomb charge was studied in gapped pseudospin-1 systems generated by an alpha – T-3 lattice. The electronic spectrum was studied as a function of the impurity strength Z alpha. However, the results and conclusions on the behavior of the flatband states as a function of the impurity strength are incomplete. In this Comment, I argue that because of the dispersionless nature of the flatband, the states spread out under the influence of a charged impurity forming a continuous band of states. I support my arguments with explicit numerical calculations which show the emergence of a continuum of states.  
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  Publisher Place of Publication Editor  
  Language Wos 000533793600004 Publication Date 2020-05-20  
  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 ; I would like to acknowledge very insightful discussions with the authors of the commented paper (V. P. Gusynin, E. V. Gorbar, and D. O. Oriekhov). F. M. Peeters is acknowledged for interesting discussions and proofreading. This research was supported by the Flemish Science Foundation through an aspirant research grant for R.V.P. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:169476 Serial 6472  
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Author Vargas Paredes, A.A.; Shanenko, A.A.; Vagov, A.; Milošević, M.V.; Perali, A. url  doi
openurl 
  Title Crossband versus intraband pairing in superconductors: signatures and consequences of the interplay Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 101 Issue 9 Pages 094516-94517  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract We analyze the paradigmatic competition between intraband and crossband Cooper-pair formation in twoband superconductors, neglected in most works to date. We derive the phase-sensitive gap equations and describe the crossover between the intraband-dominated and the crossband-dominated regimes, delimited by a “gapless” state. Experimental signatures of crosspairing comprise notable gap splitting in the excitation spectrum, non-BCS behavior of gaps versus temperature, as well as changes in the pairing symmetry as a function of temperature. The consequences of these findings are illustrated on the examples of MgB2 and Ba0.6K0.4Fe2As2.  
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  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000522074900002 Publication Date 2020-03-27  
  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 3.7 Times cited 14 Open Access  
  Notes ; This collaborative work was fostered within the international Multi Super network on Multi-condensate Superconductivity and Superfluidity [70]. The authors thank Andrea Guidini for his help during the initial stage of this work and Laura Fanfarillo for useful discussions. This work was partially supported by the Italian MIUR through the PRIN 2015 program (Contract No. 2015C5SEJJ001) and the Research Foundation -Flanders (FWO). A.A.V.-P. acknowledges support by the joint doctoral program and by the Erasmus+ exchange between the University of Antwerp and the University of Camerino. M.V.M. gratefully acknowledges support from a Visiting Professorship at the University of Camerino. A.S. and A.V. acknowledge support from the CAPES/Print Grant, Process No. 88887.333666/ 2019-00 (Brazil) and the Russian Science Foundation Project No. 18-12-00429, respectively. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:168605 Serial 6479  
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Author Conti, S.; Van der Donck, M.; Perali, A.; Peeters, F.M.; Neilson, D. url  doi
openurl 
  Title Doping-dependent switch from one- to two-component superfluidity in coupled electron-hole van der Waals heterostructures Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 101 Issue 22 Pages 220504-220506  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The hunt for high-temperature superfluidity has received new impetus from the discovery of atomically thin stable materials. Electron-hole superfluidity in coupled MoSe2-WSe2 monolayers is investigated using a mean-field multiband model that includes band splitting caused by strong spin-orbit coupling. This splitting leads to a large energy misalignment of the electron and hole bands which is strongly modified by interchanging the doping of the monolayers. The choice of doping determines if the superfluidity is tunable from one to two components.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000538941900002 Publication Date 2020-06-09  
  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 11 Open Access  
  Notes ; This work was partially supported by the Fonds Wetenschappelijk Onderzoek (FWO-Vl), the Methusalem Foundation, and the FLAG-ERA project TRANS2DTMD. We thank A. R. Hamilton and A. Vargas-Paredes for useful discussions. ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:170201 Serial 6489  
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Author Saberi-Pouya, S.; Conti, S.; Perali, A.; Croxall, A.F.; Hamilton, A.R.; Peeters, F.M.; Neilson, D. url  doi
openurl 
  Title Experimental conditions for the observation of electron-hole superfluidity in GaAs heterostructures Type A1 Journal article
  Year 2020 Publication Physical Review B Abbreviated Journal (up) Phys Rev B  
  Volume 101 Issue 14 Pages 140501-140506  
  Keywords A1 Journal article; Condensed Matter Theory (CMT)  
  Abstract The experimental parameter ranges needed to generate superfluidity in optical and drag experiments in GaAs double quantum wells are determined using a formalism that includes self-consistent screening of the Coulomb pairing interaction in the presence of the superfluid. The very different electron and hole masses in GaAs make this a particularly interesting system for superfluidity with exotic superfluid phases predicted in the BCS-Bose-Einstein condensation crossover regime. We find that the density and temperature ranges for superfluidity cover the range for which optical experiments have observed indications of superfluidity but that existing drag experiments lie outside the superfluid range. We also show that, for samples with low mobility with no macroscopically connected superfluidity, if the superfluidity survives in randomly distributed localized pockets, standard quantum capacitance measurements could detect these pockets.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000523627600001 Publication Date 2020-04-06  
  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 3.7 Times cited 13 Open Access  
  Notes ; We thank K. Das Gupta, F. Dubin, U. Siciliani de Cumis, M. Pini, and J. Waldie for illuminating discus-sions. This work was partially supported by the Flemish Science Foundation (FWO-Vl) and the Australian Government through the Australian Research Council Centre of Excellence in Future Low-Energy Electronics (Project No. CE170100039). ; Approved Most recent IF: 3.7; 2020 IF: 3.836  
  Call Number UA @ admin @ c:irua:168561 Serial 6517  
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