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“Wave-packet scattering on graphene edges in the presence of a pseudomagnetic field”. da Costa DR, Chaves A, Farias GA, Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 86, 115434 (2012). http://doi.org/10.1103/PhysRevB.86.115434
Abstract: The scattering of a Gaussian wave packet in armchair and zigzag graphene edges is theoretically investigated by numerically solving the time-dependent Schrodinger equation for the tight-binding model Hamiltonian. Our theory allows us to investigate scattering in reciprocal space, and depending on the type of graphene edge we observe scattering within the same valley, or between different valleys. In the presence of an external magnetic field, the well-known skipping orbits are observed. However, our results demonstrate that in the case of a pseudomagnetic field, induced by nonuniform strain, the scattering by an armchair edge results in a nonpropagating edge state.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 28
DOI: 10.1103/PhysRevB.86.115434
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“Wavepacket scattering of Dirac and Schrödinger particles on potential and magnetic barriers”. Rakhimov KY, Chaves A, Farias GA, Peeters FM, Journal of physics : condensed matter 23, 275801 (2011). http://doi.org/10.1088/0953-8984/23/27/275801
Abstract: We investigate the dynamics of a charged particle moving in a graphene layer and in a two-dimensional electron gas, where it obeys the Dirac and the Schrödinger equations, respectively. The charge carriers are described as Gaussian wavepackets. The dynamics of the wavepackets is studied numerically by solving both quantum-mechanical and relativistic equations of motion. The scattering of such wavepackets by step-like magnetic and potential barriers is analysed for different values of wavepacket energy and width. We find: (1) that the average position of the wavepacket does not coincide with the classical trajectory, and (2) that, for slanted incidence, the path of the centre of mass of the wavepacket does not have to penetrate the barrier during the scattering process. Trembling motion of the charged particle in graphene is observed in the absence of an external magnetic field and can be enhanced by a substrate-induced mass term.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 32
DOI: 10.1088/0953-8984/23/27/275801
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“Weakly localized biexcitons in quantum wells”. Mayrock O, Wünsche H-J, Henneberger F, Riva C, Schweigert VA, Peeters FM, Physical review : B : condensed matter and materials physics 60, 5582 (1999). http://doi.org/10.1103/PhysRevB.60.5582
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.60.5582
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“Yukawa particles confined in a channel and subject to a periodic potential : ground state and normal modes”. Carvalho JCN, Ferreira WP, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 83, 094109 (2011). http://doi.org/10.1103/PhysRevB.83.094109
Abstract: We consider a classical system of two-dimensional (2D) charged particles, interacting through a repulsive Yukawa potential exp(-r/λ)/r, and confined in a parabolic channel that limits the motion of the particles in the y direction. Along the x direction, the particles are subject to a periodic potential. The ground-state configurations and the normal-mode spectra of the system are obtained as a function of the periodicity and strength of the periodic potential (V0) and density. An interesting set of tunable ground-state configurations are found, with first- or second-order structural transitions between them. A configuration with particles aligned, perpendicular to the x direction, in each minimum of the periodic potential is obtained for V0 larger than some critical value that has a power-law dependence on the density. The phonon spectrum of different configurations was also calculated. A localization of the modes into a small frequency interval is observed for sufficiently large strength of the periodic potential, and a tunable gap in the phonon spectrum is found as a function of V0.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.83.094109
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“Anisotropic exciton Stark shift in black phosphorus”. Chaves A, Low T, Avouris P, Çakir D, Peeters FM, Physical review : B : condensed matter and materials physics 91, 155311 (2015). http://doi.org/10.1103/PhysRevB.91.155311
Abstract: We calculate the excitonic spectrum of few-layer black phosphorus by direct diagonalization of the effective mass Hamiltonian in the presence of an applied in-plane electric field. The strong attractive interaction between electrons and holes in this system allows one to investigate the Stark effect up to very high ionizing fields, including also the excited states. Our results show that the band anisotropy in black phosphorus becomes evident in the direction-dependent field-induced polarizability of the exciton.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 88
DOI: 10.1103/PhysRevB.91.155311
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“Chainlike transitions in Wigner crystals : sequential versus nonsequential”. Galvan-Moya, Misko VR, Peeters FM, Physical review : B : condensed matter and materials physics 92, 064112 (2015). http://doi.org/10.1103/PhysRevB.92.064112
Abstract: The structural transitions of the ground state of a system of repulsively interacting particles confined in a quasi-one-dimensional channel, and the effect of the interparticle interaction as well as the functional form of the confinement potential on those transitions are investigated. Although the nonsequential ordering of transitions (non-SOT), i.e., the 1 – 2 – 4 – 3 – 4 – 5 – 6 – ... sequence of chain configurations with increasing density, is widely robust as predicted in a number of theoretical studies, the sequential ordering of transitions (SOT), i.e., the 1 – 2 – 3 – 4 – 5 – 6 – ... chain, is found as the ground state for long-ranged interparticle interaction and hard-wall-like confinement potentials. We found an energy barrier between every two different phases around its transition point, which plays an important role in the preference of the system to follow either a SOT or a non-SOT. However, that preferential transition requires also the stability of the phases during the transition. Additionally, we analyze the effect of a small structural disorder on the transition between the two phases around its transition point. Our results show that a small deformation of the triangular structure changes dramatically the picture of the transition between two phases, removing in a considerable region the non-SOT in the system. This feature could explain the fact that the non-SOT is, up to now, not observed in experimental systems, and suggests a more advanced experimental setup to detect the non-SOT.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PhysRevB.92.064112
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“Diffusion of fluorine on and between graphene layers”. Sadeghi A, Neek-Amal M, Berdiyorov GR, Peeters FM, Physical review : B : condensed matter and materials physics 91, 014304 (2015). http://doi.org/10.1103/PhysRevB.91.014304
Abstract: Using first-principles calculations and reactive force field molecular dynamics simulations, we study the structural properties and dynamics of a fluorine (F) atom, either adsorbed on the surface of single layer graphene (F/GE) or between the layers of AB stacked bilayer graphene (F@ bilayer graphene). It is found that the diffusion of the F atom is very different in those cases, and that the mobility of the F atom increases by about an order of magnitude when inserted between two graphene layers. The obtained diffusion constant for F/GE is twice larger than that experimentally found for gold adatom and theoretically found for C-60 molecule on graphene. Our study provides important physical insights into the dynamics of fluorine atoms between and on graphene layers and explains the mechanism behind the separation of graphite layers due to intercalation of F atoms.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 15
DOI: 10.1103/PhysRevB.91.014304
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“Effect of ordered array of magnetic dots on the dynamics of Josephson vortices in stacked SNS Josephson junctions under DC and AC current”. Berdiyorov GR, Savel'ev S, Kusmartsev FV, Peeters FM, European physical journal : B : condensed matter and complex systems 88, 286 (2015). http://doi.org/10.1140/epjb/e2015-60628-9
Abstract: We use the anisotropic time-dependent Ginzburg-Landau theory to investigate the effect of a square array of out-of-plane magnetic dots on the dynamics of Josephson vortices (fluxons) in artificial stacks of superconducting-normal-superconducting (SNS) Josephson junctions in the presence of external DC and AC currents. Periodic pinning due to the magnetic dots distorts the triangular lattice of fluxons and results in the appearance of commensurability features in the current-voltage characteristics of the system. For the larger values of the magnetization, additional peaks appear in the voltage-time characteristics of the system due to the creation and annihilation of vortex-antivortex pairs. Peculiar changes in the response of the system to the applied current is found resulting in a “superradiant” vortex-flow state at large current values, where a rectangular lattice of moving vortices is formed. Synchronizing the motion of fluxons by adding a small ac component to the biasing dc current is realized. However, we found that synchronization becomes difficult for large magnetization of the dots due to the formation of vortex-antivortex pairs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 1
DOI: 10.1140/epjb/e2015-60628-9
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“Electric-field-driven Mott metal-insulator transition in correlated thin films : an inhomogeneous dynamical mean-field theory approach”. Bakalov P, Esfahani DN, Covaci L, Peeters FM, Tempere J, Locquet J-P, Physical review : B : condensed matter and materials physics 93, 165112 (2016). http://doi.org/10.1103/PhysRevB.93.165112
Abstract: Simulations are carried out based on the dynamical mean-field theory (DMFT) in order to investigate the properties of correlated thin films for various values of the chemical potential, temperature, interaction strength, and applied transverse electric field. Application of a sufficiently strong field to a thin film at half filling leads to the appearance of conducting regions near the surfaces of the film, whereas in doped slabs the application of a field leads to a conductivity enhancement on one side of the film and a gradual transition to the insulating state on the opposite side. In addition to the inhomogeneous DMFT, a local density approximation (LDA) is considered in which the particle density n, quasiparticle residue Z, and spectral weight at the Fermi level A(ω=0) of each layer are approximated by a homogeneous bulk environment. A systematic comparison between the two approaches reveals that the less expensive LDA results are in good agreement with the DMFT approach, except close to the metal-to-insulator transition points and in the layers immediately at the film surfaces. LDA values for n are overall more reliable than those for Z and A(ω=0). The hysteretic behavior (memory effect) characteristic of the bulk doping driven Mott transition persists in the slab.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 5
DOI: 10.1103/PhysRevB.93.165112
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“Electronic properties of triangular and hexagonal MoS2 quantum dots”. Pavlović, S, Peeters FM, Physical review : B : condensed matter and materials physics 91, 155410 (2015). http://doi.org/10.1103/PhysRevB.91.155410
Abstract: Using the tight-binding approach, we calculate the electronic structure of triangular and hexagonal MoS2 quantum dots. Due to the orbital asymmetry we show that it is possible to form quantum dots with the same shape but having different electronic properties. The electronic states of triangular and hexagonal quantum dots are explored, as well as the local and total density of states and the convergence towards the bulk spectrum with dot size is investigated. Our calculations show that: (1) edge states appear in the band gap, (2) that there are a larger number of electronic states in the conduction band as compared to the valence band, and (3) the relative number of edge states decreases with increasing dot size.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 44
DOI: 10.1103/PhysRevB.91.155410
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“Energy levels of bilayer graphene quantum dots”. da Costa DR, Zarenia M, Chaves A, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 92, 115437 (2015). http://doi.org/10.1103/PhysRevB.92.115437
Abstract: Within a tight binding approach we investigate the energy levels of hexagonal and triangular bilayer graphene (BLG) quantum dots (QDs) with zigzag and armchair edges. We study AA- and AB-(Bernal) stacked BLG QDs and obtain the energy levels in both the absence and the presence of a perpendicular electric field (i.e., biased BLG QDs). Our results show that the size dependence of the energy levels is different from that of monolayer graphene QDs. The energy spectrum of AB-stacked BLG QDs with zigzag edges exhibits edge states which spread out into the opened energy gap in the presence of a perpendicular electric field. We found that the behavior of these edges states is different for the hexagonal and triangular geometries. In the case of AA-stacked BLG QDs, the electron and hole energy levels cross each other in both cases of armchair and zigzag edges as the dot size or the applied bias increases.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.92.115437
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“Giant magnetic anisotropy in doped single layer molybdenum disulfide and fluorographene”. Sivek J, Sahin H, Partoens B, Peeters FM, Journal of physics : condensed matter 28, 195301 (2016). http://doi.org/10.1088/0953-8984/28/19/195301
Abstract: Stable monolayer materials based on existing, well known and stable two-dimensional crystal fluorographene and molybdenum disulfide are predicted to exhibit a huge magnetocrystalline anisotropy when functionalized with adsorbed transition metal atoms at vacant sides. Ab initio calculations within the density-functional theory formalism were performed to investigate the adsorption of the transitional metals in a single S (or F) vacancy of monolayer molybdenum disulfide (or fluorographene). We found strong bonding of the transitional metal atoms to the vacant sites with binding energies ranging from 2.5 to 5.2 eV. Our calculations revealed that these systems with adsorbed metal atoms exhibit a magnetic anisotropy, specifically the structures including Os and Ir show a giant magnetocrystalline anisotropy energy of 31-101 meV. Our results demonstrate the possibility of obtaining stable monolayer materials with huge magnetocrystalline anisotropy based on preexisting, well known and stable two-dimensional crystals: fluorographene and molybdenum disulfide. We believe that the results obtained here are useful not only for deeper understanding of the origin of magnetocrystalline anisotropy but also for the design of monolayer optoelectronic devices with novel functionalities.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 7
DOI: 10.1088/0953-8984/28/19/195301
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“Graphene-silicene bilayer : a nanocapacitor with permanent dipole and piezoelectricity effect”. Peymanirad F, Neek Amal M, Beheshtian J, Peeters FM, Physical review : B : condensed matter and materials physics 92, 155113 (2015). http://doi.org/10.1103/PhysRevB.92.155113
Abstract: Using density functional theory, we study the electronic properties of a graphene-silicene bilayer (GSB). A single layer of silicene binds to the graphene layer with adhesion energy of about 25 meV/atom. This adhesion energy between the two layers follows accurately the well-known -1/z(2) dispersion energy as found between two infinite parallel plates. In small flakes of GSB with hydrogenated edges, negative charge is transferred from the graphene layer to the silicene layer, producing a permanent and a switchable polar bilayer, while in an infinite GSB, the negative charge is transferred from the silicene layer to the graphene layer. The graphene-silicene bilayer is a good candidate for a nanocapacitor with piezoelectric capabilities. We found that the permanent dipole of the bilayer can be tuned by an external perpendicular electric field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.92.155113
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“Heterostructures of graphene and nitrogenated holey graphene: Moire pattern and Dirac ring”. Kang J, Horzum S, Peeters FM, Physical review : B : condensed matter and materials physics 92, 195419 (2015). http://doi.org/10.1103/PhysRevB.92.195419
Abstract: Nitrogenated holey graphene (NHG) is a recently synthesized two-dimensional material. In this paper the structural and electronic properties of heterostructures of graphene and NHG are investigated using first-principles and tight-binding calculations. Due to the lattice mismatch between NHG and graphene, the formation of a moire pattern is preferred in the graphene/NHG heterostructure, instead of a lattice-coherent structure. In moire-patterned graphene/NHG, the band gap opening at the K point is negligible, and the linear band dispersion of graphene survives. Applying an electric field modifies the coupling strength between the two atomic layers. The Fermi velocity upsilon(F) is reduced as compared to the one of pristine graphene, and its magnitude depends on the twist angle theta between graphene and NHG: For theta = 0 degrees, upsilon(F) is 30% of that of graphene, and it increases rapidly to a value of 80% with increasing theta. The heterostructure exhibits electron-hole asymmetry in upsilon(F), which is large for small theta. In NHG encapsulated between two graphene layers, a “Dirac ring” appears around the K point. Its presence is robust with respect to the relative stacking of the two graphene layers. These findings can be useful for future applications of graphene/NHG heterostructures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 33
DOI: 10.1103/PhysRevB.92.195419
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“Majorana zero-energy modes and spin current evolution in mesoscopic superconducting loop systems with spin-orbit interaction”. Zha G-Q, Covaci L, Peeters FM, Zhou S-P, Physical review : B : condensed matter and materials physics 92, 094516 (2015). http://doi.org/10.1103/PhysRevB.92.094516
Abstract: The Majorana zero modes and persistent spin current in mesoscopic d-wave-superconducting loops with spin-orbit (SO) interaction are investigated by numerically solving the spin-generalized Bogoliubov-de Gennes equations self-consistently. For some appropriate strength of the SO coupling, Majorana zero-energy states and sharp jumps of the spin-polarized currents can be observed when the highest energy levels cross the Fermi energy in the spectrum, leading to spin currents with opposite chirality flowing near the inner and outer edges of the sample. When the threaded magnetic flux turns on, four flux-dependent patterns of the persistent spin current with step-like features show up, accompanied by Majorana edge modes at flux values where the energy gap closes. Moreover, the Majorana zero mode is highly influenced by the direction of the Zeeman field. A finite in-plane field can lead to the gap opening since the inversion symmetry is broken. Remarkably, multiple Majorana zero-energy states occur in the presence of an out-of-plane field h(z), and the number of steps in the spin current evolution can be effectively tuned by the field strength due to the shift of Majorana zero modes. Finally, when the loop sample contains surface indentation defects, zero-energy modes can always show up in the presence of an appropriate h(z). Interestingly, multiple Majorana states may be present in the system with a corner defect even if h(z) = 0.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.92.094516
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“Quantum effects in a free-standing graphene lattice : path-integral against classical Monte Carlo simulations”. Brito BGA, Candido L, Hai G-Q, Peeters FM, Physical review : B : condensed matter and materials physics 92, 195416 (2015). http://doi.org/10.1103/PhysRevB.92.195416
Abstract: In order to study quantum effects in a two-dimensional crystal lattice of a free-standing monolayer graphene, we have performed both path-integral Monte Carlo (PIMC) and classical Monte Carlo (MC) simulations for temperatures up to 2000 K. The REBO potential is used for the interatomic interaction. The total energy, interatomic distance, root-mean-square displacement of the atom vibrations, and the free energy of the graphene layer are calculated. The obtained lattice vibrational energy per atom from the classical MC simulation is very close to the energy of a three-dimensional harmonic oscillator 3k(B)T. The PIMC simulation shows that quantum effects due to zero-point vibrations are significant for temperatures T < 1000 K. The quantum contribution to the lattice vibrational energy becomes larger than that of the classical lattice for T < 400 K. The lattice expansion due to the zero-point motion causes an increase of 0.53% in the lattice parameter. A minimum in the lattice parameter appears at T similar or equal to 500 K. Quantum effects on the atomic vibration amplitude of the graphene lattice and its free energy are investigated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 22
DOI: 10.1103/PhysRevB.92.195416
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“Quantum magnetotransport properties of a MoS2 monolayer”. Tahir M, Vasilopoulos P, Peeters FM, Physical review : B : condensed matter and materials physics 93, 035406 (2016). http://doi.org/10.1103/PhysRevB.93.035406
Abstract: We study transport properties of a MoS2 monolayer in the presence of a perpendicular magnetic field B. We derive and discuss its band structure and take into account spin and valley Zeeman effects. Compared to a conventional two-dimensional electron gas, these effects lead to new quantum Hall plateaus and new peaks in the longitudinal resistivity as functions of the magnetic field. The field B leads to a significant enhancement of the spin splitting in the conduction band, to a beating of the Shubnikov-de Haas (SdH) oscillations in the low-field regime, and to their splitting in the high-field regime. The Zeeman fields suppress significantly the beating of the SdH oscillations in the low-field regime and strongly enhance their splitting at high fields. The spin and valley polarizations show a similar beating pattern at low fields and are clearly separated at high fields in which they attain a value higher than 90%.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 42
DOI: 10.1103/PhysRevB.93.035406
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“Self-assembly of Janus particles into helices with tunable pitch”. Sobrino Fernandez M, Misko VR, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 92, 042309 (2015). http://doi.org/10.1103/PhysRevE.92.042309
Abstract: Janus particles present an important class of building blocks for directional assembly. These are compartmentalized colloids with two different hemispheres. In this work we consider a three-dimensional model of Janus spheres that contain one hydrophobic and one charged hemisphere. Using molecular dynamics simulations, we study the morphology of these particles when confined in a channel-like environment. The interplay between the attractive and repulsive forces on each particle gives rise to a rich phase space where the relative orientation of each particle plays a dominant role in the formation of large-scale clusters. The interest in this system is primarily due to the fact that it could give a better understanding of the mechanisms of the formation of polar membranes. A variety of ordered membranelike morphologies is found consisting of single and multiple connected chain configurations. The helicity of these chains can be chosen by simply changing the salt concentration of the solution. Special attention is given to the formation of Bernal spirals. These helices are composed of regular tetrahedra and are known to exhibit nontrivial translational and rotational symmetry.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 18
DOI: 10.1103/PhysRevE.92.042309
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“Significant effect of stacking on the electronic and optical properties of few-layer black phosphorus”. Çakir D, Sevik C, Peeters FM, Physical review : B : condensed matter and materials physics 92, 165406 (2015). http://doi.org/10.1103/PhysRevB.92.165406
Abstract: The effect of the number of stacking layers and the type of stacking on the electronic and optical properties of bilayer and trilayer black phosphorus are investigated by using first-principles calculations within the framework of density functional theory. We find that inclusion of many-body effects (i.e., electron-electron and electron-hole interactions) modifies strongly both the electronic and optical properties of black phosphorus. While trilayer black phosphorus with a particular stacking type is found to be a metal by using semilocal functionals, it is predicted to have an electronic band gap of 0.82 eV when many-body effects are taken into account within the G(0)W(0) scheme. Though different stacking types result in similar energetics, the size of the band gap and the optical response of bilayer and trilayer phosphorene are very sensitive to the number of layers and the stacking type. Regardless of the number of layers and the type of stacking, bilayer and trilayer black phosphorus are direct band gap semiconductors whose band gaps vary within a range of 0.3 eV. Stacking arrangements that are different from the ground state structure in both bilayer and trilayer black phosphorus exhibit significant modified valence bands along the zigzag direction and result in larger hole effective masses. The optical gap of bilayer (trilayer) black phosphorus varies by 0.4 (0.6) eV when changing the stacking type. The calculated binding energy of the bound exciton hardly changes with the type of stacking and is found to be 0.44 (0.30) eV for bilayer (trilayer) phosphorous.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 127
DOI: 10.1103/PhysRevB.92.165406
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“Spin- and valley-dependent transport through arrays of ferromagnetic silicene junctions”. Missault N, Vasilopoulos P, Vargiamidis V, Peeters FM, Van Duppen B, Physical review : B : condensed matter and materials physics 92, 195423 (2015). http://doi.org/10.1103/PhysRevB.92.195423
Abstract: We study ballistic transport of Dirac fermions in silicene through arrays of barriers, of width d, in the presence of an exchange field M and a tunable potential of height U or depth-U. The spin-and valley-resolved conductances as functions of U or M, exhibit resonances away from the Dirac point (DP) and close to it a pronounced dip that becomes a gap when a critical electric field E-z is applied. This gap widens by increasing the number of barriers and can be used to realize electric field-controlled switching of the current. The spin p(s) and valley p(v) polarizations of the current near the DP increase with Ez or M and can reach 100% for certain of their values. These field ranges widen significantly by increasing the number of barriers. Also, ps and pv oscillate nearly periodically with the separation between barriers or wells and can be inverted by reversing M.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 54
DOI: 10.1103/PhysRevB.92.195423
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“Structural and phononic characteristics of nitrogenated holey graphene”. Sahin H, Physical review : B : condensed matter and materials physics 92, 085421 (2015). http://doi.org/10.1103/PhysRevB.92.085421
Abstract: Recent experimental studies showed that formation of a two-dimensional crystal structure of nitrogenated holey graphene (NHG) is possible. Similar to graphene, NHGs have an atomically thin and strong crystal structure. Using first-principles calculations, we investigate the structural, phononic, and thermal properties of monolayer NHG crystal. Our charge analysis reveals that the charged holey sites of NHG provide a reactive ground for further functionalization by adatoms or molecules. We also found that similar to graphene, the NHG structure has quite high-frequency phonon modes and the presence of nitrogen atoms leads to the emergence of additional vibrational modes. Our phonon analysis reveals the presence of three characteristic Raman-active modes of NHG. Furthermore, the analysis of constant-volume heat capacity showed that the NHG structure has a linear temperature dependence in the low-temperature region. The strong lattice structure and unique thermal properties of the NHG crystal structure are desirable in nanoscale device applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 49
DOI: 10.1103/PhysRevB.92.085421
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“TiS3 nanoribbons : width-independent band gap and strain-tunable electronic properties”. Kang J, Sahin H, Ozaydin HD, Senger RT, Peeters FM, Physical review : B : condensed matter and materials physics 92, 075413 (2015). http://doi.org/10.1103/PhysRevB.92.075413
Abstract: The electronic properties, carrier mobility, and strain response of TiS3 nanoribbons (TiS3 NRs) are investigated by first-principles calculations. We found that the electronic properties of TiS3 NRs strongly depend on the edge type (a or b). All a-TiS3 NRs are metallic with a magnetic ground state, while b-TiS3 NRs are direct band gap semiconductors. Interestingly, the size of the band gap and the band edge position are almost independent of the ribbon width. This feature promises a constant band gap in a b-TiS3 NR with rough edges, where the ribbon width differs in different regions. The maximum carrier mobility of b-TiS3 NRs is calculated by using the deformation potential theory combined with the effective mass approximation and is found to be of the order 10(3) cm(2) V-1 s(-1). The hole mobility of the b-TiS3 NRs is one order of magnitude lower, but it is enhanced compared to the monolayer case due to the reduction in hole effective mass. The band gap and the band edge position of b-TiS3 NRs are quite sensitive to applied strain. In addition we investigate the termination of ribbon edges by hydrogen atoms. Upon edge passivation, the metallic and magnetic features of a-TiS3 NRs remain unchanged, while the band gap of b-TiS3 NRs is increased significantly. The robust metallic and ferromagnetic nature of a-TiS3 NRs is an essential feature for spintronic device applications. The direct, width-independent, and strain-tunable band gap, as well as the high carrier mobility, of b-TiS3 NRs is of potential importance in many fields of nanoelectronics, such as field-effect devices, optoelectronic applications, and strain sensors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 55
DOI: 10.1103/PhysRevB.92.075413
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“The 30-band k . p theory of valley splitting in silicon thin layers”. Cukaric NA, Partoens B, Tadic MZ, Arsoski VV, Peeters FM, Journal of physics : condensed matter 28, 195303 (2016). http://doi.org/10.1088/0953-8984/28/19/195303
Abstract: The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k . p theory. The system composed of a few nm thick Si layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K-0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
DOI: 10.1088/0953-8984/28/19/195303
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“Theory of anharmonic phonons in two-dimensional crystals”. Michel KH, Costamagna, Peeters FM, Physical review : B : condensed matter and materials physics 91, 134302 (2015). http://doi.org/10.1103/PhysRevB.91.134302
Abstract: Anharmonic effects in an atomic monolayer thin crystal with honeycomb lattice structure are investigated by analytical and numerical lattice dynamical methods. Starting from a semiempirical model for anharmonic couplings of third and fourth orders, we study the in-plane and out-of-plane (flexural) mode components of the generalized wave vector dependent Gruneisen parameters, the thermal tension and the thermal expansion coefficients as a function of temperature and crystal size. From the resonances of the displacement-displacement correlation functions, we obtain the renormalization and decay rate of in-plane and flexural phonons as a function of temperature, wave vector, and crystal size in the classical and in the quantum regime. Quantitative results are presented for graphene. There, we find that the transition temperature T-alpha from negative to positive thermal expansion is lowered with smaller system size. Renormalization of the flexural mode has the opposite effect and leads to values of T-alpha approximate to 300 K for systems of macroscopic size. Extensive numerical analysis throughout the Brillouin zone explores various decay and scattering channels. The relative importance of normal and umklapp processes is investigated. The work is complementary to crystalline membrane theory and computational studies of anharmonic effects in two-dimensional crystals.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PhysRevB.91.134302
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“Tuning the magnetic anisotropy in single-layer crystal structures”. Torun E, Sahin H, Bacaksiz C, Senger RT, Peeters FM, Physical review : B : condensed matter and materials physics 92, 104407 (2015). http://doi.org/10.1103/PhysRevB.92.104407
Abstract: The effect of an applied electric field and the effect of charging are investigated on themagnetic anisotropy (MA) of various stable two-dimensional (2D) crystals such as graphene, FeCl2, graphone, fluorographene, and MoTe2 using first-principles calculations. We found that themagnetocrystalline anisotropy energy of Co-on-graphene and Os-doped-MoTe2 systems change linearly with electric field, opening the possibility of electric field tuningMAof these compounds. In addition, charging can rotate the easy-axis direction ofCo-on-graphene andOs-doped-MoTe2 systems from the out-of-plane (in-plane) to in-plane (out-of-plane) direction. The tunable MA of the studied materials is crucial for nanoscale electronic technologies such as data storage and spintronics devices. Our results show that controlling the MA of the mentioned 2D crystal structures can be realized in various ways, and this can lead to the emergence of a wide range of potential applications where the tuning and switching of magnetic functionalities are important.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 37
DOI: 10.1103/PhysRevB.92.104407
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“Two-shell vortex and antivortex dynamics in a Corbino superconducting disk”. Cabral LRE, de Aquino BRCHT, de Souza Silva CC, Milošević, MV, Peeters FM, Physical review : B : condensed matter and materials physics 93, 014515 (2016). http://doi.org/10.1103/PhysRevB.93.014515
Abstract: We examine theoretically the dynamics of two vortex shells in pinning-free superconducting thin disks in the Corbino geometry. In the first considered case, the inner shell is composed of vortices and the outer one of antivortices, corresponding to a state induced by the stray field of an off-plane magnetic dipole placed on top of the superconductor. In the second considered case, both shells comprise vortices induced by a homogeneous external field. We derive the equation of motion for each shell within the Bardeen-Stephen model and study the dynamics analytically by assuming both shells are rigid and commensurate. In both cases, two distinct regimes for vortex shell motion are identified: For low applied currents the entire configuration rotates rigidly, while above a threshold current the shells decouple from each other and rotate at different angular velocities. Analytical expressions for the decoupling current, the recombination time in the decoupled phases, as well as the voltage-current characteristics are presented. Our analytical results are in excellent agreement with numerical molecular dynamics simulations of the full many-vortex problem.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.93.014515
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“Validity criteria for Fermi's golden rule scattering rates applied to metallic nanowires”. Moors K, Sorée B, Magnus W, Journal of physics : condensed matter 28, 365302 (2016). http://doi.org/10.1088/0953-8984/28/36/365302
Abstract: Fermi's golden rule underpins the investigation of mobile carriers propagating through various solids, being a standard tool to calculate their scattering rates. As such, it provides a perturbative estimate under the implicit assumption that the effect of the interaction Hamiltonian which causes the scattering events is sufficiently small. To check the validity of this assumption, we present a general framework to derive simple validity criteria in order to assess whether the scattering rates can be trusted for the system under consideration, given its statistical properties such as average size, electron density, impurity density et cetera. We derive concrete validity criteria for metallic nanowires with conduction electrons populating a single parabolic band subjected to different elastic scattering mechanisms: impurities, grain boundaries and surface roughness.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 2
DOI: 10.1088/0953-8984/28/36/365302
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“Finite-temperature Wigner solid and other phases of ripplonic polarons on a helium film”. Klimin SN, Tempère J, Misko VR, Wouters M, European physical journal : B : condensed matter and complex systems 89, 172 (2016). http://doi.org/10.1140/EPJB/E2016-70149-8
Abstract: Electrons on liquid helium can form different phases depending on density, and temperature. Also the electron-ripplon coupling strength influences the phase diagram, through the formation of so-called “ripplonic polarons”, that change how electrons are localized, and that shifts the transition between the Wigner solid and the liquid phase. We use an all-coupling, finite-temperature variational method to study the formation of a ripplopolaron Wigner solid on a liquid helium film for different regimes of the electron-ripplon coupling strength. In addition to the three known phases of the ripplopolaron system (electron Wigner solid, polaron Wigner solid, and electron fluid), we define and identify a fourth distinct phase, the ripplopolaron liquid. We analyse the transitions between these four phases and calculate the corresponding phase diagrams. This reveals a reentrant melting of the electron solid as a function of temperature. The calculated regions of existence of the Wigner solid are in agreement with recent experimental data.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 1
DOI: 10.1140/EPJB/E2016-70149-8
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“Strained graphene Hall bar”. Milovanovic SP, Peeters FM, Journal of physics : condensed matter 29, 075601 (2017). http://doi.org/10.1088/1361-648X/AA50D3
Abstract: The effects of strain, induced by a Gaussian bump, on the magnetic field dependent transport properties of a graphene Hall bar are investigated. The numerical simulations are performed using both classical and quantum mechanical transport theory and we found that both approaches exhibit similar characteristic features. The effects of the Gaussian bump are manifested by a decrease of the bend resistance, RB, around zero-magnetic field and the occurrence of side-peaks in RB. These features are explained as a consequence of bump-assisted scattering of electrons towards different terminals of the Hall bar. Using these features we are able to give an estimate of the size of the bump. Additional oscillations in RB are found in the quantum description that are due to the population/depopulation of Landau levels. The bump has a minor influence on the Hall resistance even for very high values of the pseudo-magnetic field. When the bump is placed outside the center of the Hall bar valley polarized electrons can be collected in the leads.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 12
DOI: 10.1088/1361-648X/AA50D3
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“Calculation of binary and ternary metallic immiscible clusters with icosahedral structures”. Dzhurakhalov AA, Atanasov I, Hou M, Physical review : B : condensed matter and materials physics , 115415 (2008). http://doi.org/10.1103/PHYSREVB.77.115415
Abstract: Recently, core-shell Ag-Co, Ag-Cu, and “onionlike” Cu-Co equilibrium configurations were predicted in the case of isolated face centered cubic (fcc) bimetallic clusters, and three shell onionlike configurations were predicted in the case of ternary metallic clusters with spherical and truncated octahedral morphologies. In the present paper, immiscible binary CuCo and ternary AgCuCo clusters with icosahedral structures are studied as functions of their size and composition. Clusters studied are formed by 13, 55, 147, 309, and 561 atoms corresponding to the five smallest possible closed shell icosahedral structures. An embedded atom model potential is used to describe their cohesion. Equilibrium configurations are investigated by means of Metropolis Monte Carlo free energy minimization in the (NPT) canonical ensemble. Most simulations are achieved at 10 and 300 K. The effect of temperature on segregation ordering is systematically investigated. Selected cases are used to identify the effect of size and composition on melting. In contrast with fcc clusters, homogeneous onionlike configurations of binary clusters are not predicted. When it is allowed by the composition, a complete outer shell is formed by Cu in binary Cu-Co clusters and by Ag in ternary Ag-Cu-Co clusters. Depending on temperature, Co may precipitate into decahedral groups under the Cu vertices of the icosahedra in binary clusters, while the Co-Cu configuration in ternary clusters drastically depends on the Ag coating. Despite the multicomponent character of the clusters and the immiscibility of the species forming them, for most compositions and sizes, equilibrium structures remain close to perfectly icosahedral at 10 K as well as at 300 K.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PHYSREVB.77.115415
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