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“Influence of electron-electron interaction on the cyclotron resonance spectrum of magnetic quantum dots containing few electrons”. Nga TTN, Peeters FM, Physical review : B : condensed matter and materials physics 83, 075419 (2011). http://doi.org/10.1103/PhysRevB.83.075419
Abstract: The configuration interaction method is used to obtain the magneto-optical absorption spectrum of a few-electron (Ne=1,2,,5) quantum dot containing a single magnetic ion. We find that the IR spectrum (the position, the number, and the oscillator strength of the cyclotron resonance peaks) depends on the strength of the Coulomb interaction, the number of electrons, and the position of the magnetic ion. We find that the Kohn theorem is no longer valid as a consequence of the electron-spin-magnetic-ion-spin-exchange interaction.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.83.075419
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“Influence of impurities and surface defects on the flux-induced current in mesoscopic d-wave superconducting loops”. Zha G-Q, Milošević, MV, Zhou S-P, Peeters FM, Physical review : B : condensed matter and materials physics 84, 132501 (2011). http://doi.org/10.1103/PhysRevB.84.132501
Abstract: We investigated the magnetic flux dependence of the supercurrent in mesoscopic d-wave superconducting loops, containing impurities and surface defects, by numerically solving the Bogoliubovde Gennes equations self-consistently. In the presence of impurities, bound states arise close to the Fermi energy. In the case of a single impurity, the flux-induced current is found to be suppressed. This can be different when more impurities are introduced in the sample due to the quantum interference effect, which depends sensitively on the relative position between the impurities. We further analyze the effect of small surface defects at the inner or outer edge of the loop, and show that indentation and bulge defects have pronounced and different effects on the supercurrent.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 13
DOI: 10.1103/PhysRevB.84.132501
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“Landau levels in asymmetric graphene trilayer”. Sena SHR, Pereira JM, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 84, 205448 (2011). http://doi.org/10.1103/PhysRevB.84.205448
Abstract: The electronic spectrum of three coupled graphene layers (graphene trilayers) is investigated in the presence of an external magnetic field. We obtain analytical expressions for the Landau level spectrum for both the ABA and ABC type of stacking, which exhibit very different dependence on the magnetic field. We show that layer asymmetry and an external gate voltage can strongly influence the properties of the system.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 30
DOI: 10.1103/PhysRevB.84.205448
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“Lattice thermal properties of graphane : thermal contraction, roughness, and heat capacity”. Neek-Amal M, Peeters FM, Physical review : B : condensed matter and materials physics 83, 235437 (2011). http://doi.org/10.1103/PhysRevB.83.235437
Abstract: Using atomistic simulations, we determine the roughness and the thermal properties of a suspended graphane sheet. As compared to graphene, we found that (i) hydrogenated graphene has a larger thermal contraction, (ii) the roughness exponent at room temperature is smaller, i.e., ≃ 1.0 versus ≃ 1.2 for graphene, (iii) the wavelengths of the induced ripples in graphane cover a wide range corresponding to length scales in the range 30125 Å at room temperature, and (iv) the heat capacity of graphane is estimated to be 29.32±0.23 J/mol K, which is 14.8% larger than that for graphene, i.e., 24.98±0.14 J/mol K. Above 1500 K, we found that graphane buckles when its edges are supported in the x-y plane.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 42
DOI: 10.1103/PhysRevB.83.235437
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“Metallic nanograins : spatially nonuniform pairing induced by quantum confinement”. Croitoru MD, Shanenko AA, Kaun CC, Peeters FM, Physical review : B : condensed matter and materials physics 83, 214509 (2011). http://doi.org/10.1103/PhysRevB.83.214509
Abstract: It is well known that the formation of discrete electron levels strongly influences the pairing in metallic nanograins. Here, we focus on another effect of quantum confinement in superconducting grains that was not studied previously, i.e., spatially nonuniform pairing. This effect is very significant when single-electron levels form bunches and/or a kind of shell structure. We find that, in highly symmetric grains, the order parameter can exhibit variations with position by an order of magnitude. Nonuniform pairing is closely related to a quantum-confinement-induced modification of the pairing-interaction matrix elements and size-dependent pinning of the chemical potential to groups of degenerate or nearly degenerate levels. For illustrative purposes, we consider spherical metallic nanograins and also rectangular shapes. We show that the relevant matrix elements are, as a rule, enhanced in the presence of quantum confinement, which favors spatial variations of the order parameter, compensating the corresponding energy cost. The size-dependent pinning of the chemical potential further increases the spatial variation of the pair condensate. The role of nonuniform pairing is smaller in less symmetric confining geometries and/or in the presence of disorder. However, it always remains of importance when the energy spacing between discrete electron levels δ is approaching the scale of the bulk gap ΔB, i.e., δ>0.10.2 ΔB.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 23
DOI: 10.1103/PhysRevB.83.214509
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“Origin of the hysteresis of the current voltage characteristics of superconducting microbridges near the critical temperature”. Vodolazov DY, Peeters FM, Physical review : B : condensed matter and materials physics 84, 094511 (2011). http://doi.org/10.1103/PhysRevB.84.094511
Abstract: The current voltage (IV) characteristics of short [with length L less than or similar to xi(T)] and long [L >> xi(T)] microbridges are theoretically investigated near the critical temperature of the superconductor. Calculations are made in the nonlocal (local) limit when the inelastic relaxation length due to electron-phonon interactions L(in) = (D tau(in))(1/2) is larger (smaller) than the temperature-dependent coherence length xi(T) (D is the diffusion coefficient, tau(in) is the inelastic relaxation time of the quasiparticle distribution function). We find that, in both limits, the origin of the hysteresis in the IV characteristics is mainly connected with the large time scale over which the magnitude of the order parameter varies in comparison with the time-scale variation of the superconducting phase difference across the microbridge in the resistive state. In the nonlocal limit, the time-averaged heating and cooling of quasiparticles are found in different areas of the microbridge, which are driven, respectively, by oscillations of the order parameter and the electric field. We show that, by introducing an additional term in the time-dependent Ginzburg-Landau equation, it is possible to take into account the cooling effect in the local limit too.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.84.094511
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“Parity-fluctuation induced enlargement of the ratio \DeltaE/kBTc in metallic grains”. Croitoru MD, Shanenko AA, Peeters FM, Axt VM, Physical review : B : condensed matter and materials physics 84, 214518 (2011). http://doi.org/10.1103/PhysRevB.84.214518
Abstract: We investigate how the interplay of quantum confinement and particle number-parity fluctuations affects superconducting correlations in ultra-small metallic grains. Using the number-parity projected BCS formalism we calculate the critical temperature and the excitation gap as a function of the grain size for grains with even and odd number of confined carriers. We show that the experimentally observed anomalous increase of the coupling ratio ΔE/kBTc with decreasing superconducting grain size can be attributed to an enhancement of the number-parity fluctuations in ultra-small grains.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 14
DOI: 10.1103/PhysRevB.84.214518
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“Rectification by an imprinted phase in a Josephson junction”. Berdiyorov GR, Milošević, MV, Covaci L, Peeters FM, Physical review letters 107, 177008 (2011). http://doi.org/10.1103/PhysRevLett.107.177008
Abstract: A Josephson phase shift can be induced in a Josephson junction by a strategically nearby pinned Abrikosov vortex (AV). For an asymmetric distribution of an imprinted phase along the junction (controlled by the position of the AV) such a simple system is capable of rectification of ac current in a broad and tunable frequency range. The resulting rectified voltage is a consequence of the directed motion of a Josephson antivortex which forms a pair with the AV when at local equilibrium. The proposed realization of the ratchet potential by an imprinted phase is more efficient than the asymmetric geometry of the junction itself, is easily realizable experimentally, and provides rectification even in the absence of an applied magnetic field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 28
DOI: 10.1103/PhysRevLett.107.177008
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“Scattering of Dirac electrons by circular mass barriers : valley filter and resonant scattering”. Masir MR, Matulis A, Peeters FM, Physical review : B : condensed matter and materials physics 84, 245413 (2011). http://doi.org/10.1103/PhysRevB.84.245413
Abstract: The scattering of two-dimensional (2D) massless Dirac electrons is investigated in the presence of a random array of circular mass barriers. The inverse momentum relaxation time and the Hall factor are calculated and used to obtain parallel and perpendicular resistivity components within linear transport theory. We found a nonzero perpendicular resistivity component which has opposite sign for electrons in the different K and K′ valleys. This property can be used for valley filter purposes. The total cross section for scattering on penetrable barriers exhibits resonances due to the presence of quasibound states in the barriers that show up as sharp gaps in the cross section while for Schrödinger electrons they appear as peaks.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 32
DOI: 10.1103/PhysRevB.84.245413
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“Single neutral excitons confined in AsBr3 in situ etched InGaAs quantum rings”. Ding F, Li B, Akopian N, Perinetti U, Chen YH, Peeters FM, Rastelli A, Zwiller V, Schmidt OG, Journal of nanoelectronics and optoelectronics 6, 51 (2011). http://doi.org/10.1166/jno.2011.1132
Abstract: We observe the evolution of single self-assembled semiconductor quantum dots into quantum rings during AsBr3 in situ etching. The direct three-dimensional imaging of In(Ga)As nanostructures embedded in GaAs matrix is demonstrated by selective wet chemical etching combined with atomic force microscopy. Single neutral excitons confined in these quantum rings are studied by magneto-photoluminescence. Oscillations in the exciton radiative recombination energy and in the emission intensity are observed under an applied magnetic field. Further, we demonstrate that the period of the oscillations can be tuned by a gate potential that modifies the exciton confinement. The experimental results, combined with calculations, indicate that the exciton Aharonov-Bohm effect may account for the observed effects.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 0.497
Times cited: 3
DOI: 10.1166/jno.2011.1132
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“Spin and momentum filtering of electrons on the surface of a topological insulator”. Wu Z, Peeters FM, Chang K, Applied physics letters 98, 162101 (2011). http://doi.org/10.1063/1.3581887
Abstract: We investigate theoretically the transport properties of Dirac fermions on the surface of a three-dimensional topological insulator. Dirac electrons can be totally reflected in front of a magnetic/electric p-n junction. For a p-n-p structure, multiple total internal reflections at the interfaces result in the bound states in the channel, which behaves like an electronic waveguide. This p-n-p like structure exhibits spin and momentum filtering features and could be used as a spin and/or charge diode.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 33
DOI: 10.1063/1.3581887
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“Structure and energetics of hydrogen chemisorbed on a single graphene layer to produce graphane”. Dzhurakhalov AA, Peeters FM, Carbon 49, 3258 (2011). http://doi.org/10.1016/j.carbon.2011.03.052
Abstract: Chemisorption of hydrogen on graphene is studied using atomistic simulations with the second generation of reactive empirical bond order Brenner inter-atomic potential. The lowest energy adsorption sites and the most important metastable sites are determined. The H concentration is varied from a single H atom, to clusters of H atoms up to full coverage. We found that when two or more H atoms are present, the most stable configurations of H chemisorption on a single graphene layer are ortho hydrogen pairs adsorbed on one side or on both sides of the graphene sheet. The latter has the highest hydrogen binding energy. The next stable configuration is the orthopara pair combination, and then para hydrogen pairs. The structural changes of graphene caused by chemisorbed hydrogen are discussed and are compared with existing experimental data and other theoretical calculations. The obtained results will be useful for nanoengineering of graphene by hydrogenation and for hydrogen storage.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Integrated Molecular Plant Physiology Research (IMPRES)
Impact Factor: 6.337
Times cited: 46
DOI: 10.1016/j.carbon.2011.03.052
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“Study on the giant positive magnetoresistance and Hall effect in ultrathin graphite flakes”. Vansweevelt R, Mortet V, D' Haen J, Ruttens bart, van Haesendonck C, Partoens B, Peeters FM, Wagner P, Physica status solidi : A : applications and materials science 208, 1252 (2011). http://doi.org/10.1002/pssa.201001206
Abstract: In this paper, we report on the electronic transport properties of mesoscopic, ultrathin graphite flakes with a thickness corresponding to a stack of 150 graphene layers. The graphite flakes show an unexpectedly strong positive magnetoresistance (PMR) already at room temperature, which scales in good approximation with the square of the magnetic field. Furthermore, we show that the resistivity is unaffected by magnetic fields oriented in plane with the graphene layers. Hall effect measurements indicate that the charge carriers are p-type and their concentration increases with increasing temperature while the mobility is decreasing. The Hall voltage is non-linear in higher magnetic fields. Possible origins of the observed effects are discussed. Ball and stick model of the two topmost carbon layers of the hexagonal graphite structure.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.775
Times cited: 8
DOI: 10.1002/pssa.201001206
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“Superconducting nanowires : new type of BCS-BEC crossover driven by quantum-size effects”. Shanenko AA, Croitoru MD, Vagov A, Peeters FM, , 119 (2011). http://doi.org/10.1007/978-94-007-0044-4_9
Abstract: We show that a superconducting quantum nanowire undergoes a new type of BCS-BEC crossover each time when an electron subband approaches the Fermi surface. In this case the longitudinal Cooper-pair size drops by two-three orders of magnitude down to a few nanometers. This unconventional BCS-BEC crossover is driven by quantum-size effects rather than by tuning the fermion-fermion interaction.
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
DOI: 10.1007/978-94-007-0044-4_9
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“Superconducting proximity effect in graphene under inhomogeneous strain”. Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 84, 241401 (2011). http://doi.org/10.1103/PhysRevB.84.241401
Abstract: The interplay between quantum Hall states and Cooper pairs is usually hindered by the suppression of the superconducting state due to the strong magnetic fields needed to observe the quantum Hall effect. From this point of view, graphene is special since it allows the creation of strong pseudomagnetic fields due to strain. We show that in a Josephson junction made of strained graphene, Cooper pairs will diffuse into the strained region. The pair correlation function will be sublattice polarized due to the polarization of the local density of states in the zero pseudo-Landau level. We uncover two regimes: (1) one in which the cyclotron radius is larger than the junction length, in which case the supercurrent will be enhanced, and (2) the long junction regime where the supercurrent is strongly suppressed because the junction becomes an insulator. In the latter case quantized Hall states form and Andreev scattering at the normal/superconducting interface will induce edge states. Our numerical calculation has become possible due to an extension of the Chebyshev-Bogoliubovde Gennes method to computations on video cards (GPUs).
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.84.241401
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“D- shallow donor near a semiconductor-metal and a semiconductor-dielectric interface”. Hao YL, Djotyan AP, Avetisyan AA, Peeters FM, Journal of physics : condensed matter 23, 115303 (2011). http://doi.org/10.1088/0953-8984/23/11/115303
Abstract: The ground state energy and the extent of the wavefunction of a negatively charged donor (D − ) located near a semiconductormetal or a semiconductordielectric interface are obtained. We apply the effective mass approximation and use a variational two-electron wavefunction that takes into account the influence of all image charges that arise due to the presence of the interface, as well as the correlation between the two electrons bound to the donor. For a semiconductormetal interface, the D − binding energy is enhanced for donor positions d > 1.5aB (aB is the effective Bohr radius) due to the additional attraction of the electrons with their images. When the donor approaches the interface (i.e. d < 1.5aB) the D − binding energy drops and eventually it becomes unbound. For a semiconductordielectric (or a semiconductorvacuum) interface the D − binding energy is reduced for any donor position as compared to the bulk case and the system becomes rapidly unbound when the donor approaches the interface.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 5
DOI: 10.1088/0953-8984/23/11/115303
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“Topological confinement in an antisymmetric potential in bilayer graphene in the presence of a magnetic field”. Zarenia M, Pereira JM, Peeters FM, Farias G de A, Nanoscale research letters 6, 452 (2011). http://doi.org/10.1186/1556-276X-6-452
Abstract: We investigate the effect of an external magnetic field on the carrier states that are localized at a potential kink and a kink-antikink in bilayer graphene. These chiral states are localized at the interface between two potential regions with opposite signs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.833
Times cited: 4
DOI: 10.1186/1556-276X-6-452
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“Tunable optical Aharonov-Bohm effect in a semiconductor quantum ring”. Li B, Peeters FM, Physical review : B : condensed matter and materials physics 83, 115448 (2011). http://doi.org/10.1103/PhysRevB.83.115448
Abstract: By applying an electric field perpendicular to a semiconductor quantum ring we show that it is possible to modify the single particle wave function between quantum dot (QD)-like and ring-like. The constraints on the geometrical parameters of the quantum ring to realize such a transition are derived. With such a perpendicular electric field we are able to tune the Aharanov-Bohm (AB) effect for both the single particle and for excitons. The tunability is in both the strength of the AB effect as well as in its periodicity. We also investigate the strain induce potential inside the self-assembled quantum ring and the effect of the strain on the AB effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 25
DOI: 10.1103/PhysRevB.83.115448
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“Tuning of anisotropy in two-electron quantum dots by spin-orbit interactions”. Liu Y, Cheng F, Li XJ, Peeters FM, Chang K, Applied physics letters 99, 032102 (2011). http://doi.org/10.1063/1.3610961
Abstract: We investigate the influence of the spin-orbit interactions (SOIs) on the electron distribution and the optical absorption of a two-electron quantum dot. It is shown that the interplay between the SOIs makes the two-electron quantum dot behave like two laterally coupled quantum dots and the anisotropic distribution can be rotated from [110] to [11®0] by reversing the direction of the perpendicular electric field and detect it through the optical absorption spectrum.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 8
DOI: 10.1063/1.3610961
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“Tuning of the spin-orbit interaction in a quantum dot by an in-plane magnetic field”. Nowak MP, Szafran B, Peeters FM, Partoens B, Pasek WJ, Physical review : B : condensed matter and materials physics 83, 245324 (2011). http://doi.org/10.1103/PhysRevB.83.245324
Abstract: Using an exact-diagonalization approach we show that one- and two-electron InAs quantum dots exhibit an avoided crossing in the energy spectra that is induced by the spin-orbit coupling in the presence of an in-plane external magnetic field. The width of the avoided crossings depends strongly on the orientation of the magnetic field, which reveals the intrinsic anisotropy of the spin-orbit-coupling interactions. We find that for specific orientations of the magnetic field avoided crossings vanish. A value of this orientation can be used to extract the ratio of the strength of Rashba and Dresselhaus interactions. The spin-orbit anisotropy effects for various geometries and orientations of the confinement potential are discussed. Our analysis explains the physics behind the recent measurements performed on a gated self-assembled quantum dot [ S. Takahashi et al. Phys. Rev. Lett. 104 246801 (2010)].
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 27
DOI: 10.1103/PhysRevB.83.245324
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“Valley-dependent brewster angles and Goos-Hänchen effect in strained graphene”. Wu Z, Zhai F, Peeters FM, Xu HQ, Chang K, Physical review letters 106, 176802 (2011). http://doi.org/10.1103/PhysRevLett.106.176802
Abstract: We demonstrate theoretically how local strains in graphene can be tailored to generate a valley-polarized current. By suitable engineering of local strain profiles, we find that electrons in opposite valleys (K or K′) show different Brewster-like angles and Goos-Hänchen shifts, exhibiting a close analogy with light propagating behavior. In a strain-induced waveguide, electrons in K and K′ valleys have different group velocities, which can be used to construct a valley filter in graphene without the need for any external fields.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 235
DOI: 10.1103/PhysRevLett.106.176802
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“Vibrational properties of graphene fluoride and graphane”. Peelaers H, Hernández-Nieves AD, Leenaerts O, Partoens B, Peeters FM, Applied physics letters 98, 051914 (2011). http://doi.org/10.1063/1.3551712
Abstract: The vibrational properties of graphene fluoride and graphane are studied using ab initio calculations. We find that both sp(3) bonded derivatives of graphene have different phonon dispersion relations and phonon densities of states as expected from the different masses associated with the attached atoms of fluorine and hydrogen, respectively. These differences manifest themselves in the predicted temperature behavior of the constant-volume specific heat of both compounds. (C) 2011 American Institute of Physics. [doi:10.1063/1.3551712]
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 66
DOI: 10.1063/1.3551712
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“Vortex manipulation in superconducting films with tunable magnetic topology”. Milošević, MV, Peeters FM, Jankó, B, Superconductor science and technology 24, 024001 (2011). http://doi.org/10.1088/0953-2048/24/2/024001
Abstract: Using a combination of the phenomenological GinzburgLandau theory and micromagnetic simulations, we study properties of a superconducting film with an array of soft magnetic dots on top. An external in-plane magnetic field gradually drives the magnets from an out-of-plane or magnetic vortex state to an in-plane single-domain state, which changes spatially the distribution of the superconducting condensate. If induced by the magnets, the vortexantivortex molecules exhibit rich transitions as a function of the applied in-plane field. At the same time, we show how the magnetic dots act as very effective dynamic pinning centers for vortices in an applied perpendicular magnetic field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.878
Times cited: 8
DOI: 10.1088/0953-2048/24/2/024001
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“Vortex-vortex interaction in bulk superconductors : Ginzburg-Landau theory”. Chaves A, Peeters FM, Farias GA, Milošević, MV, Physical review : B : condensed matter and materials physics 83, 054516 (2011). http://doi.org/10.1103/PhysRevB.83.054516
Abstract: The vortex-vortex interaction potential in bulk superconductors is calculated within the Ginzburg-Landau (GL) theory and is obtained from a numerical solution of a set of two coupled nonlinear GL differential equations for the vector potential and the superconducting order parameter, where the merger of vortices into a giant vortex is allowed. Further, the interaction potentials between a vortex and a giant vortex and between a vortex and an antivortex are obtained for both type-I and type-II superconductors. Our numerical results agree asymptotically with the analytical expressions for large intervortex separations that are available in the literature. We propose empirical expressions valid over the full interaction range, which are fitted to our numerical data for different values of the GL parameter.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 31
DOI: 10.1103/PhysRevB.83.054516
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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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“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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“Analytic treatment of vortex states in cylindrical superconductors in applied axial magnetic field”. Ludu A, Van Deun J, Milošević, MV, Cuyt A, Peeters FM, Journal of mathematical physics 51, 082903 (2010). http://doi.org/10.1063/1.3470767
Abstract: We solve the linear GinzburgLandau (GL) equation in the presence of a uniform magnetic field with cylindrical symmetry and we find analytic expressions for the eigenfunctions in terms of the confluent hypergeometric functions. The discrete spectrum results from an implicit equation associated to the boundary conditions and it is resolved in analytic form using the continued fractions formalism. We study the dependence of the spectrum and the eigenfunctions on the sample size and the surface conditions for solid and hollow cylindrical superconductors. Finally, the solutions of the nonlinear GL formalism are constructed as expansions in the linear GL eigenfunction basis and selected by minimization of the free energy. We present examples of vortex states and their energies for different samples in enhancing/suppressing superconductivity surroundings.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.077
Times cited: 10
DOI: 10.1063/1.3470767
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“Calorimetric properties of mesoscopic superconducting disks, rings, and cylinders”. Xu B, Milošević, MV, Peeters FM, Physical review : B : condensed matter and materials physics 81, 064501 (2010). http://doi.org/10.1103/PhysRevB.81.064501
Abstract: The thermal signatures of superconductivity in mesoscopic disks, rings and cylinders are calculated within the Ginzburg-Landau theory. In an applied perpendicular magnetic field H the heat capacity of mesoscopic samples shows a strong dependence on the realized vortex state; discontinuities are found at the critical field for different vorticities, as well as at the superconducting-to-normal state transition. The same applies to the intermediate state of type-I superconductors. Even the subtle changes in the fluxoid distribution inside the sample leave clear signatures on heat capacity, which is particularly useful for fully three-dimensional samples whose interior is often inaccessible by magnetometry. The heat-capacity jump ΔC(H) at the critical temperature exhibits quasiperiodic modulations as a function of magnetic field. In mesoscopic superconducting rings, these oscillations provide calorimetric verification of the Little-Parks effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.81.064501
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“Carbon clusters: from ring structures to nanographene”. Kosimov DP, Dzhurakhalov AA, Peeters FM, Physical review : B : condensed matter and materials physics 81, 195414 (2010). http://doi.org/10.1103/PhysRevB.81.195414
Abstract: The lowest-energy configurations of Cn(n≤55) clusters are obtained using the energy-minimization technique with the conjugate gradient method where a modified Brenner potential is invoked to describe the carbon and hydrocarbon interaction. We found that the ground-state configuration consists of a single ring for small number of C atoms and multiring structures are found with increasing n, which can be in planar, bowl-like or caplike form. Contrary to previous predictions, the binding energy Eb does not show even-odd oscillations and only small jumps are found in the Eb(n) curve as a consequence of specific types of edges or equivalently the number of secondary atoms. We found that hydrogenation of the edge atoms may change the ground-state configuration of the nanocluster. In both cases we determined the magic clusters. Special attention is paid to trigonal and hexagonal shaped carbon clusters and to clusters having a graphenelike configuration. Trigonal clusters are never the ground state while hexagonal-shaped clusters are only the ground state when they have zigzag edges.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Integrated Molecular Plant Physiology Research (IMPRES); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 55
DOI: 10.1103/PhysRevB.81.195414
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“Combined molecular dynamics: continuum study of phase transitions in bulk metals under ultrashort pulsed laser irradiation”. Wendelen W, Dzhurakhalov AA, Peeters FM, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 114, 5652 (2010). http://doi.org/10.1021/jp907385n
Abstract: The phase transition processes induced by ultrashort, 100 fs pulsed laser irradiation of Au, Cu, and Ni are studied by means of a combined atomistic-continuum approach. A moderately low absorbed laser fluence range, from 200 to 600 J/m2 is considered to study phase transitions by means of a local and a nonlocal order parameter. At low laser fluences, the occurrence of layer-by-layer evaporation has been observed, which suggests a direct solid to vapor transition. The calculated amount of molten material remains very limited under the conditions studied, especially for Ni. Therefore, our results show that a kinetic equation that describes a direct solid to vapor transition might be the best approach to model laser-induced phase transitions by continuum models. Furthermore, the results provide more insight into the applicability of analytical superheating theories that were implemented in continuum models and help the understanding of nonequilibrium phase transitions.
Keywords: A1 Journal article; Integrated Molecular Plant Physiology Research (IMPRES); Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 2
DOI: 10.1021/jp907385n
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