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“Microscopic theory of the rhombohedral phase and transition to the monoclinic phase of solid C70”. Nikolaev AV, Michel KH, Physical review : B : condensed matter and materials physics 54, 12733 (1996). http://doi.org/10.1103/PhysRevB.54.12733
Abstract: Starting from a model of microscopic interactions between C-70 molecules, we have developed a theory which describes the orientational dynamics and its coupling to lattice displacements in the rhombohedral phase of C-70 fullerite. The Landau free energy is calculated. We obtain a first-order phase transition to a monoclinic structure with the space group P2(1)/m. The transition is driven by the condensation of orientational quadrupoles at the F point of the Brillouin zone of the rhombohedral lattice. We find no evidence that the monoclinic structure is connected with the freezing in of orientations around the fivefold molecular axis. We calculate the lattice strains that are associated with the transition to the monoclinic structure. The theory is compared with a range of experimental data on the phase transition.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 5
DOI: 10.1103/PhysRevB.54.12733
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“Impurity band and magnetic-field-induced metal-insulator transition in a doped GaAs/AlxGa1-xAs superlattice”. Hilber W, Helm M, Peeters FM, Alavi K, Pathak RN, Physical review : B : condensed matter and materials physics 53, 6919 (1996). http://doi.org/10.1103/PhysRevB.53.6919
Abstract: A combination of infrared spectroscopy and magnetotransport is used to investigate the impurity band and the magnetic-field-induced metal-insulator transition in n-type GaAs/AlxGa1-xAs superlattices. The dropping of the Fermi level from the conduction band into the impurity band upon increasing magnetic field is observed in a sample doped to n=4n(c), where n(c) is the critical density according to the Mott criterion. The metal-insulator transition takes place while the Fermi level is in the impurity band, with no qualitative change from the metallic to the insulating side. Due to the anisotropy of the superlattice band structure, the metal-insulator transition is shifted to higher magnetic field, when the magnetic field is tilted away from the growth axis towards the layer planes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 14
DOI: 10.1103/PhysRevB.53.6919
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“Microscopic theory of orientational disorder and lattice instability in solid C70”. Callebaut AK, Michel KH, Physical review : B : condensed matter and materials physics 52, 15279 (1995). http://doi.org/10.1103/PhysRevB.52.15279
Abstract: We have developed a microscopic theory which describes the orientational dynamics of C-70 molecules and its coupling to lattice displacements in the face-centered-cubic phase of C-70 fullerite. The single-molecule orientational density distribution in the disordered phase is calculated. The ferroelastic transition to the rhombohedral phase is investigated. The discontinuity of the orientational order parameter at the phase transition is calculated. It is found that the transition leads to a stretching of the primitive unit cell along a [111] cubic direction. A softening of the elastic constant c(44) at the transition is predicted.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 20
DOI: 10.1103/PhysRevB.52.15279
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“Magnetotransport in a pseudomorphic GaAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure with a Si \delta-doping layer”. van der Burgt M, Karavolas VC, Peeters FM, Singleton J, Nicholas RJ, Herlach F, Harris JJ, Van Hove M, Borghs G, Physical review : B : condensed matter and materials physics 52, 12218 (1995). http://doi.org/10.1103/PhysRevB.52.12218
Abstract: Magnetotransport properties of a pseudomorphic GsAs/Ga0.8In0.2As/Ga0.75Al0.25As heterostructure are investigated in pulsed magnetic fields up to 50 T and at temperatures of T = 1.4 and 4.2 K. The structure studied consists of a Si delta layer parallel to a Ga0.8In0.2As quantum well (QW). The dark electron density of the structure is n(c) = 1.67 x 10(16) m(-2). By illumination the density can be increased up to a factor of 4; this way the second subband in the Ga0.08In0.2As QW can become populated as well as the Si delta layer. The presence of electrons in the delta layer results in drastic changes in the transport data, especially at magnetic fields beyond 30 T. The phenomena observed are interpreted as (i) magnetic freeze-out of carriers in the delta layer when a low density of electrons is present in the delta layer, and (ii) quantization of the electron motion in the two-dimensional electron gases in both the Ga0.8In0.2As QW and the Si delta layer in the case of high densities. These conclusions are corroborated by the numerical results of our theoretical model. We obtain satisfactory agreement between model and experiment.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 43
DOI: 10.1103/PhysRevB.52.12218
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“Nonlinear Schrödinger equation on a circle”. Smondyrev MA, Vansant P, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 52, 11231 (1995). http://doi.org/10.1103/PhysRevB.52.11231
Abstract: The nonlinear Schrodinger equation is solved on an infinitesimal thin ring or circle. We obtained the exact real wave functions with their corresponding energies for the ground state and the excited states. Critical values of the circle perimeter are found at which the ground state changes its structure and additional higher excited states appear. Also, the complex wave functions that correspond to energy levels with finite angular momentum are studied.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 5
DOI: 10.1103/PhysRevB.52.11231
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“One-dimensional bipolaron in the strong coupling limit”. Vansant P, Smondyrev MA, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 50, 12524 (1994). http://doi.org/10.1103/PhysRevB.50.12524
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 15
DOI: 10.1103/PhysRevB.50.12524
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“Growth mode and electronic-structure of the epitaxial C60(111)/GeS(001) interface”. Gensterblum G, Hevesi K, Han BY, Yu LM, Pireaux JJ, Thiry PA, Caudano R, Lucas AA, Bernaerts D, Amelinckx S, Van Tendeloo G, Bendele G, Buslaps T, Johnson RL, Foss M, Feidenhans’l R, Le Lay G;, Physical review : B : condensed matter and materials physics 50, 11981 (1994). http://doi.org/10.1103/PhysRevB.50.11981
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.736
Times cited: 81
DOI: 10.1103/PhysRevB.50.11981
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“Electrophonon resonances in a quasi-two-dimensional electron system”. Xu W, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 48, 1562 (1993). http://doi.org/10.1103/PhysRevB.48.1562
Abstract: When the energy difference between two electric subbands in a quasi-two-dimensional electron system equals a LO-phonon energy, resonant scattering will occur. This leads to an enhancement of the scattering rate and, consequently, to a suppression of the conductivity. Changing the energy difference between the electric subbands (e.g., through a gate) leads to a series of electrophonon resonances in the conductivity. A detailed study is made of this effect for different confinement potentials. We found that the scattering processes where the emission of a phonon is involved are very important for the electrophonon resonance and that the size of the effect decreases with increasing temperature.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 45
DOI: 10.1103/PhysRevB.48.1562
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“Quantum transport of a two-dimensional electron gas in a spatially modulated magnetic field”. Peeters FM, Vasilopoulos P, Physical review : B : condensed matter and materials physics 47, 1466 (1993). http://doi.org/10.1103/PhysRevB.47.1466
Abstract: Electrical transport properties of a two-dimensional electron gas axe studied in the presence of a perpendicular magnetic field B modulated weakly and periodically along one direction, B = (B + B0 cos Kx)z, with B0 much less than B, K = 2pi/a, and a being the period of the modulation. B0 is taken constant or proportional to B. The Landau levels broaden into bands and their width, proportional to the modulation strength B0, oscillates with B and gives rise to oscillations in the magnetoresistance at low B. These oscillations reflect the commensurability between the cyclotron diameter at the Fermi level and the period a and consequently hey are distinctly different from the Shubnikov-de Ha.as ones, at higher B, in period and temperature dependence. The bandwidth at the Fermi energy can be one order of magnitude larger, at low B, than that of the electric case for equal modulation strengths. The resulting magnetoresistance oscillations have a much higher amplitude than those of the electric case with which they are out of phase. Explicit asymptotic expressions are derived for the temperature dependence of the transport coefficients. The case when both electric and magnetic modulations are present is also considered. The position of the resulting oscillations depends on the ratio delta between the two modulation strengths. When the modulations are out of phase there is no shift in the position of the oscillations when delta varies and for a particular value of delta the oscillations are suppressed.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 169
DOI: 10.1103/PhysRevB.47.1466
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“Polaron-cyclotron-resonance spectrum resulting from interface- and slab-phonon modes in a GaAs/AlAs quantum well”. Hai GQ, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 47, 10358 (1993). http://doi.org/10.1103/PhysRevB.47.10358
Abstract: The effects of interface optical-phonon and confined slab LO-phonon modes on the polaron cyclotron-resonance frequency are investigated for a GaAs/AlAs quantum well. Using degenerate second-order perturbation theory, the polaron Landau levels are calculated and the polaron resonant region is investigated. In order to know the relative importance of the different resonant frequencies we present a full calculation of the magneto-optical absorption spectrum. At a fixed magnetic field we found four different peaks in the absorption spectrum. The relative oscillator strength of the different peaks changes with increasing magnetic field. For comparative purposes, the polaron Landau levels and cyclotron mass are also calculated using only the bulk LO-phonon modes. The influence of the finiteness of the confinement potential is investigated. We found that the interface-phonon modes influence the magnetopolaron resonance considerably near the optical-phonon frequencies for narrow wells. In the limit of zero magnetic field we recover our previous results and in the case of an infinite-barrier quantum well we are able to recover the results for a two- and three-dimensional system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 69
DOI: 10.1103/PhysRevB.47.10358
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“Streaming-to-accumulation transition in a 2-dimensional electron-system in a polar semiconductor”. Xu W, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 46, 7571 (1992). http://doi.org/10.1103/PhysRevB.46.7571
Abstract: Hot-electron transport is studied for a two-dimensional electron gas coupled to longitudinal-optical phonons in crossed electric and magnetic fields. At low electric and high magnetic fields the electrons are accumulated, while at high electric fields they are in a streaming state. We develop a streaming-to-accumulation transition model and compare the results with that from a Monte Carlo simulation.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 13
DOI: 10.1103/PhysRevB.46.7571
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“Streaming-to-accumulation transition in a two-dimensional electron system in a polar semiconductor”. Wen X, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 46, 7571 (1992). http://doi.org/10.1103/PhysRevB.46.7571
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 13
DOI: 10.1103/PhysRevB.46.7571
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“Microscopic model of surfaces in orientationally disordered ionic crystals : the (001) surface of KCN”. Zieliński P, Michel KH, Physical review : B : condensed matter and materials physics 46, 4806 (1992). http://doi.org/10.1103/PhysRevB.46.4806
Abstract: The crystallographic structure and the distribution of orientations of molecular ions are studied near the surface in an orientationally disordered crystal with the use of a Green-function formalism. The orientational degrees of freedom are treated by means of symmetry-adapted functions of angular coordinates. The structure of the (001) surface of KCN in its cubic fcc phase is then predicted using the existing data on the interaction of the ions K+ and CN-. A local antiferroelectric and antiferroelastic order i shown to exist in the surface region. The magnitude of the order and the spatial extent of the ordered re ion increase as the temperature approaches the point of the phase transition to the ordered phase. The,influence of the external electric field on the structure of the surface is predicted.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 4
DOI: 10.1103/PhysRevB.46.4806
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“Electrical and thermal-properties of a 2-dimensional electron-gas in a one-dimensional periodic potential”. Peeters FM, Vasilopoulos P, Physical review : B : condensed matter and materials physics 46, 4667 (1992). http://doi.org/10.1103/PhysRevB.46.4667
Abstract: We investigate the influence of a periodic weak modulation along the x direction on the electrical and thermal properties of a two-dimensional electron gas in the presence of a perpendicular magnetic field. The modulation lifts the degeneracy of the Landau levels and leads to one-dimensional magnetic bands whose bandwidth oscillates as a function of the magnetic field. At weak magnetic fields this gives rise to the Weiss oscillations in the magnetoresistance, discovered recently, which have a very weakly temperature-dependent amplitude and a period proportional to square-root n(e), when n(e) is the electron density. Diffusion-current contributions, proportional to the square of the bandwidth, dominate rho(xx), and collisional contributions, varying approximately as the square of the density of states, dominate rho(yy). The result is that rho(xx) and rho(yy) oscillate out of phase as observed. Asymptotic analytical expressions are presented for the conductivity tensor. Similar oscillations, of much smaller amplitude, occur in the thermodynamic quantities, such as the magnetization, the susceptibility, and the specific heat. We also predict oscillations in the Hall resistance, the cyclotron resonance position, the linewidth, as well as in the thermal conductivity and thermopower. The components of the thermal-resistance tensor have a magnetic-field dependence similar to that of the electrical-resistivity tensor.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.736
Times cited: 148
DOI: 10.1103/PhysRevB.46.4667
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“Dispersion of longitudinal plasmons for a quasi-two-dimensional electron gas”. Backes WH, Peeters FM, Brosens F, Devreese JT, Physical review : B : condensed matter and materials physics 45, 8437 (1992). http://doi.org/10.1103/PhysRevB.45.8437
Abstract: Confinement of electrons in ultrathin metallic films leads to subbands. By increasing the thickness of the electron layer, the subbands will dissolve into a quasicontinuum, with the number of electrons per unit volume kept constant. Within the random-phase approximation, the two-dimensional plasmon, which originally follows Stern's dispersion relation, becomes a longitudinal surface plasmon. The plasmon excitations of a model metallic film are investigated by including all subbands. Single-particle excitations, which exhibit the depolarization shift, converge into the plasma excitation spectrum. With further increases in the film thickness, the bulk plasmon arises and the surface plasmon remains. Our analysis shows how quantum size effects evolve into hydrodynamical classical size effects with increasing thickness of the film.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 37
DOI: 10.1103/PhysRevB.45.8437
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“Strong-coupling analysis of large bipolarons in 2 and 3 dimensions”. Verbist G, Smondyrev MA, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 45, 5262 (1992). http://doi.org/10.1103/PhysRevB.45.5262
Abstract: In the limit of strong electron-phonon coupling, we use either a Pekar-type or an oscillator wave function for the center-of-mass coordinate and either a Coulomb or an oscillator wave function for the relative coordinate, and are able to reproduce all the results from the literature for the large-bipolaron binding energy. Lower bounds are constructed for the critical ratio eta(c) of dielectric constants below which bipolarons can exist. It is found that, in the strong-coupling limit, the stability region for bipolaron formation is much larger in two dimensions (2D) than in 3D. We introduce a model that combines the averaging of the relative coordinate over the asymptotically best wave function with a path-integral treatment of the center-of-mass motion. The stability region for bipolaron formation is increased compared with the full path-integral treatment at large values of the coupling constant alpha. The critical values are alpha(c) almost-equal-to 9.3 in 3D and alpha(c) almost-equal-to 4.5 in 2D. Phase diagrams for the presented models are also obtained in both 2D and 3D.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 68
DOI: 10.1103/PhysRevB.45.5262
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“Strong-coupling analysis of large bipolarons in two and three dimensions”. Verbist G, Smondyrev MA, Peeters FM, Devreese JT, Physical review : B : condensed matter and materials physics 45, 5262 (1992). http://doi.org/10.1103/PhysRevB.45.5262
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Impact Factor: 3.736
Times cited: 68
DOI: 10.1103/PhysRevB.45.5262
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“Ginzburg-Landau surface energy of multiband superconductors : derivation and application to selected systems”. Bekaert J, Bringmans L, Milošević, MV, Journal of physics : condensed matter 35, 325602 (2023). http://doi.org/10.1088/1361-648X/ACD217
Abstract: We determine the energy of an interface between a multiband superconducting and a normal half-space, in presence of an applied magnetic field, based on a multiband Ginzburg-Landau (GL) approach. We obtain that the multiband surface energy is fully determined by the critical temperature, electronic densities of states, and superconducting gap functions associated with the different band condensates. This furthermore yields an expression for the thermodynamic critical magnetic field, in presence of an arbitrary number of contributing bands. Subsequently, we investigate the sign of the surface energy as a function of material parameters, through numerical solution of the GL equations. Here, we consider two distinct cases: (i) standard multiband superconductors with attractive interactions, and (ii) a three-band superconductor with a chiral ground state with phase frustration, arising from repulsive interband interactions. Furthermore, we apply this approach to several prime examples of multiband superconductors, such as metallic hydrogen and MgB2, based on microscopic parameters obtained from first-principles calculations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACD217
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“Intercalation of argon in honeycomb structures towards promising strategy for rechargeable Li-ion batteries”. Duden EI, Savaci U, Turan S, Sevik C, Demiroglu I, Journal of physics : condensed matter 35, 085301 (2023). http://doi.org/10.1088/1361-648X/ACA8E7
Abstract: High-performance rechargeable batteries are becoming very important for high-end technologies with their ever increasing application areas. Hence, improving the performance of such batteries has become the main bottleneck to transferring high-end technologies to end users. In this study, we propose an argon intercalation strategy to enhance battery performance via engineering the interlayer spacing of honeycomb structures such as graphite, a common electrode material in lithium-ion batteries (LIBs). Herein, we systematically investigated the LIB performance of graphite and hexagonal boron nitride (h-BN) when argon atoms were sent into between their layers by using first-principles density-functional-theory calculations. Our results showed enhanced lithium binding for graphite and h-BN structures when argon atoms were intercalated. The increased interlayer space doubles the gravimetric lithium capacity for graphite, while the volumetric capacity also increased by around 20% even though the volume was also increased. The ab initio molecular dynamics simulations indicate the thermal stability of such graphite structures against any structural transformation and Li release. The nudged-elastic-band calculations showed that the migration energy barriers were drastically lowered, which promises fast charging capability for batteries containing graphite electrodes. Although a similar level of battery promise was not achieved for h-BN material, its enhanced battery capabilities by argon intercalation also support that the argon intercalation strategy can be a viable route to enhance such honeycomb battery electrodes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/ACA8E7
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“Magnus induced diode effect for skyrmions in channels with periodic potentials”. Souza JCB, Vizarim NP, Reichhardt CJO, Reichhardt C, Venegas PA, Journal of physics : condensed matter 35, 015804 (2023). http://doi.org/10.1088/1361-648X/AC9CC5
Abstract: Using a particle based model, we investigate the skyrmion dynamical behavior in a channel where the upper wall contains divots of one depth and the lower wall contains divots of a different depth. Under an applied driving force, skyrmions in the channels move with a finite skyrmion Hall angle that deflects them toward the upper wall for -x direction driving and the lower wall for +x direction driving. When the upper divots have zero height, the skyrmions are deflected against the flat upper wall for -x direction driving and the skyrmion velocity depends linearly on the drive. For +x direction driving, the skyrmions are pushed against the lower divots and become trapped, giving reduced velocities and a nonlinear velocity-force response. When there are shallow divots on the upper wall and deep divots on the lower wall, skyrmions get trapped for both driving directions; however, due to the divot depth difference, skyrmions move more easily under -x direction driving, and become strongly trapped for +x direction driving. The preferred -x direction motion produces what we call a Magnus diode effect since it vanishes in the limit of zero Magnus force, unlike the diode effects observed for asymmetric sawtooth potentials. We show that the transport curves can exhibit a series of jumps or dips, negative differential conductivity, and reentrant pinning due to collective trapping events. We also discuss how our results relate to recent continuum modeling on a similar skyrmion diode system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
DOI: 10.1088/1361-648X/AC9CC5
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“Aluminum and lithium sulfur batteries : a review of recent progress and future directions”. Akgenc B, Sarikurt S, Yagmurcukardes M, Ersan F, Journal Of Physics-Condensed Matter 33, 253002 (2021). http://doi.org/10.1088/1361-648X/ABFA5E
Abstract: Advanced materials with various micro-/nanostructures have attracted plenty of attention for decades in energy storage devices such as rechargeable batteries (ion- or sulfur based batteries) and supercapacitors. To improve the electrochemical performance of batteries, it is uttermost important to develop advanced electrode materials. Moreover, the cathode material is also important that it restricts the efficiency and practical application of aluminum-ion batteries. Among the potential cathode materials, sulfur has become an important candidate material for aluminum-ion batteries cause of its considerable specific capacity. Two-dimensional materials are currently potential candidates as electrodes from lab-scale experiments to possible pragmatic theoretical studies. In this review, the fundamental principles, historical progress, latest developments, and major problems in Li-S and Al-S batteries are reviewed. Finally, future directions in terms of the experimental and theoretical applications have prospected.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
DOI: 10.1088/1361-648X/ABFA5E
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“Transition-metal adatoms on 2D-GaAs: a route to chiral magnetic 2D materials by design”. González-García A, López-Pérez W, González-Hernández R, Bacaksiz C, Šabani D, Milošević, MV, Peeters FM, Journal Of Physics-Condensed Matter 33, 145803 (2021). http://doi.org/10.1088/1361-648X/abe077
Abstract: Using relativistic density-functional calculations, we examine the magneto-crystalline anisotropy and exchange properties of transition-metal atoms adsorbed on 2D-GaAs. We show that single Mn and Mo atom (Co and Os) strongly bind on 2D-GaAs, and induce local out-of-plane (in-plane) magnetic anisotropy. When a pair of TM atoms is adsorbed on 2D-GaAs in a close range from each other, magnetisation properties change (become tunable) with respect to concentrations and ordering of the adatoms. In all cases, we reveal presence of strong Dzyaloshinskii–Moriya interaction. These results indicate novel pathways towards two-dimensional chiral magnetic materials by design, tailored for desired applications in magneto-electronics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 1
DOI: 10.1088/1361-648X/abe077
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“Effect of zitterbewegung on the propagation of wave packets in ABC-stacked multilayer graphene : an analytical and computational approach”. Lavor IR, da Costa DR, Chaves A, Sena SHR, Farias GA, Van Duppen B, Peeters FM, Journal Of Physics-Condensed Matter 33, 095503 (2021). http://doi.org/10.1088/1361-648X/ABCD7F
Abstract: The time evolution of a low-energy two-dimensional Gaussian wave packet in ABC-stacked n-layer graphene (ABC-NLG) is investigated. Expectation values of the position (x, y) of center-of-mass and the total probability densities of the wave packet are calculated analytically using the Green's function method. These results are confirmed using an alternative numerical method based on the split-operator technique within the Dirac approach for ABC-NLG, which additionally allows to include external fields and potentials. The main features of the zitterbewegung (trembling motion) of wave packets in graphene are demonstrated and are found to depend not only on the wave packet width and initial pseudospin polarization, but also on the number of layers. Moreover, the analytical and numerical methods proposed here allow to investigate wave packet dynamics in graphene systems with an arbitrary number of layers and arbitrary potential landscapes.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 5
DOI: 10.1088/1361-648X/ABCD7F
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“Inhomogeneous superconductivity and quasilinear magnetoresistance at amorphous LaTiO₃/SrTiO₃, interfaces”. Lebedev N, Stehno M, Rana A, Gauquelin N, Verbeeck J, Brinkman A, Aarts J, Journal Of Physics-Condensed Matter 33, 055001 (2020). http://doi.org/10.1088/1361-648X/ABC102
Abstract: We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO) heterostructures. In spite of 2D growth observed in reflection high energy electron diffraction, transmission electron microscopy images revealed that the samples tend to amorphize. Still, we observe that the structures are conducting, and some of them exhibit high conductance and/or superconductivity. We established that conductivity arises mainly on the STO side of the interface, and shows all the signs of the two-dimensional electron gas usually observed at interfaces between STO and LTO or LaAlO3, including the presence of two electron bands and tunability with a gate voltage. Analysis of magnetoresistance (MR) and superconductivity indicates the presence of spatial fluctuations of the electronic properties in our samples. That can explain the observed quasilinear out-of-plane MR, as well as various features of the in-plane MR and the observed superconductivity.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.7
Times cited: 1
DOI: 10.1088/1361-648X/ABC102
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“Strain and electric field tuning of semi-metallic character WCrCO₂, MXenes with dual narrow band gap”. Bafekry A, Akgenc B, Ghergherehchi M, Peeters FM, Journal Of Physics-Condensed Matter 32, 355504 (2020). http://doi.org/10.1088/1361-648X/AB8E88
Abstract: Motivated by the recent successful synthesis of double-M carbides, we investigate structural and electronic properties of WCrC and WCrCO2 monolayers and the effects of biaxial and out-of-plane strain and electric field using density functional theory. WCrC and WCrCO2 monolayers are found to be dynamically stable. WCrC is metallic and WCrCO2 display semi-metallic character with narrow band gap, which can be controlled by strain engineering and electric field. WCrCO2 monolayer exhibits a dual band gap which is preserved in the presence of an electric field. The band gap of WCrCO2 monolayer increases under uniaxial strain while it becomes metallic under tensile strain, resulting in an exotic 2D double semi-metallic behavior. Our results demonstrate that WCrCO2 is a new platform for the study of novel physical properties in two-dimensional Dirac materials and which may provide new opportunities to realize high-speed low-dissipation devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 45
DOI: 10.1088/1361-648X/AB8E88
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“Magnetic field induced vortices in graphene quantum dots”. Lavor IR, da Costa DR, Chaves A, Farias GA, Macedo R, Peeters FM, Journal Of Physics-Condensed Matter 32, 155501 (2020). http://doi.org/10.1088/1361-648X/AB6463
Abstract: The energy spectrum and local current patterns in graphene quantum dots (QD) are investigated for different geometries in the presence of an external perpendicular magnetic field. Our results demonstrate that, for specific geometries and edge configurations, the QD exhibits vortex and anti-vortex patterns in the local current density, in close analogy to the vortex patterns observed in the probability density current of semiconductor QD, as well as in the order parameter of mesoscopic superconductors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 5
DOI: 10.1088/1361-648X/AB6463
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“Two-dimensional hydrogenated buckled gallium arsenide: an ab initio study”. Gonzalez-Garcia A, Lopez-Perez W, Gonzalez-Hernandez R, Rivera-Julio J, Espejo C, Milošević, MV, Peeters FM, Journal Of Physics-Condensed Matter 32, 145502 (2020). http://doi.org/10.1088/1361-648X/AB6043
Abstract: First-principles calculations have been carried out to investigate the stability, structural and electronic properties of two-dimensional (2D) hydrogenated GaAs with three possible geometries: chair, zigzag-line and boat configurations. The effect of van der Waals interactions on 2D H-GaAs systems has also been studied. These configurations were found to be energetic and dynamic stable, as well as having a semiconducting character. Although 2D GaAs adsorbed with H tends to form a zigzag-line configuration, the energy differences between chair, zigzag-line and boat are very small which implies the metastability of the system. Chair and boat configurations display a – direct bandgap nature, while pristine 2D-GaAs and zigzag-line are indirect semiconductors. The bandgap sizes of all configurations are also hydrogen dependent, and wider than that of pristine 2D-GaAs with both PBE and HSE functionals. Even though DFT-vdW interactions increase the adsorption energies and reduce the equilibrium distances of H-GaAs systems, it presents, qualitatively, the same physical results on the stability and electronic properties of our studied systems with PBE functional. According to our results, 2D buckled gallium arsenide is a good candidate to be synthesized by hydrogen surface passivation as its group III-V partners 2D buckled gallium nitride and boron nitride. The hydrogenation of 2D-GaAs tunes the bandgap of pristine 2D-GaAs, which makes it a potential candidate for optoelectronic applications in the blue and violet ranges of the visible electromagnetic spectrum.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.7
Times cited: 2
DOI: 10.1088/1361-648X/AB6043
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“Physical properties of epitaxial SrMnO2.5−δFγoxyfluoride films”. Wang J, Shin Y, Gauquelin N, Yang Y, Lee C, Jannis D, Verbeeck J, Rondinelli JM, May SJ, Journal of physics : condensed matter 31, 365602 (2019). http://doi.org/10.1088/1361-648X/ab2414
Abstract: Recently, topotactic fluorination has become an alternative way of doping epitaxial perovskite oxides through anion substitution to engineer their electronic properties instead of the more commonly used cation substitution. In this work, epitaxial oxyfluoride SrMnO2.5−δ F γ films were synthesized via topotactic fluorination of SrMnO2.5 films using polytetrafluoroethylene as the fluorine source. Oxidized SrMnO3 films were also prepared for comparison with the fluorinated samples. The F content, probed by x-ray photoemission spectroscopy, was systematically controlled by adjusting fluorination conditions. Electronic transport measurements reveal that increased F content (up to γ = 0.14) systematically increases the electrical resistivity, despite the nominal electron-doping induced by F substitution for O in these films. In contrast, oxidized SrMnO3 exhibits a decreased resistivity and conduction activation energy. A blue-shift of optical absorption features occurs with increasing F content. Density functional theory calculations indicate that F acts as a scattering center for electronic transport, controls the observed weak ferromagnetic behavior of the films, and reduces the inter-band optical transitions in the manganite films. These results stand in contrast to bulk electron-doped La1−x Ce x MnO3, illustrating how aliovalent anionic substitutions can yield physical behavior distinct from A-site substituted perovskites with the same nominal B-site oxidation states.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.649
Times cited: 5
DOI: 10.1088/1361-648X/ab2414
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“Tunable 2D-gallium arsenide and graphene bandgaps in a graphene/GaAs heterostructure : an ab initio study”. Gonzalez-Garcia A, Lopez-Perez W, Gonzalez-Hernandez R, Rodriguez JA, Milošević, MV, Peeters FM, Journal of physics : condensed matter 31, 265502 (2019). http://doi.org/10.1088/1361-648X/AB0D70
Abstract: The bandgap behavior of 2D-GaAs and graphene have been investigated with van der Waals heterostructured into a yet unexplored graphene/GaAs bilayer, under both uniaxial stress along c axis and different planar strain distributions. The 2D-GaAs bandgap nature changes from Gamma-K indirect in isolated monolayer to Gamma-Gamma direct in graphene/GaAs bilayer. In the latter, graphene exhibits a bandgap of 5 meV. The uniaxial stress strongly affects the graphene electronic bandgap, while symmetric in-plane strain does not open the bandgap in graphene. Nevertheless, it induces remarkable changes on the GaAs bandgap-width around the Fermi level. However, when applying asymmetric in-plane strain to graphene/GaAs, the graphene sublattice symmetry is broken, and the graphene bandgap is open at the Fermi level to a maximum width of 814 meV. This value is much higher than that reported for just graphene under asymmetric strain. The Gamma-Gamma direct bandgap of GaAs remains unchanged in graphene/ GaAs under different types of applied strain. The analyses of phonon dispersion and the elastic constants yield the dynamical and mechanical stability of the graphene/GaAs system, respectively. The calculated mechanical properties for bilayer heterostructure are better than those of their constituent monolayers. This finding, together with the tunable graphene bandgap not only by the strength but also by the direction of the strain, enhance the potential for strain engineering of ultrathin group-III-V electronic devices hybridized by graphene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 10
DOI: 10.1088/1361-648X/AB0D70
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“Phase transition and field effect topological quantum transistor made of monolayer MoS2”. Simchi H, Simchi M, Fardmanesh M, Peeters FM, Journal of physics : condensed matter 30, 235303 (2018). http://doi.org/10.1088/1361-648X/AAC050
Abstract: We study topological phase transitions and topological quantum field effect transistor in monolayer molybdenum disulfide (MoS2) using a two-band Hamiltonian model. Without considering the quadratic (q(2)) diagonal term in the Hamiltonian, we show that the phase diagram includes quantum anomalous Hall effect, quantum spin Hall effect, and spin quantum anomalous Hall effect regions such that the topological Kirchhoff law is satisfied in the plane. By considering the q(2) diagonal term and including one valley, it is shown that MoS2 has a non-trivial topology, and the valley Chern number is non-zero for each spin. We show that the wave function is (is not) localized at the edges when the q(2) diagonal term is added (deleted) to (from) the spin-valley Dirac mass equation. We calculate the quantum conductance of zigzag MoS2 nanoribbons by using the nonequilibrium Green function method and show how this device works as a field effect topological quantum transistor.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 2
DOI: 10.1088/1361-648X/AAC050
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