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“Infrared to terahertz absorption window in mono- and multi-layer graphene systems”. Xiao YM, Xu W, Peeters FM, Optics communications 328, 135 (2014). http://doi.org/10.1016/j.optcom.2014.04.079
Abstract: We present a theoretical study on optical properties such as optical conductance and light transmission coefficient for mono- and multi-layer graphene systems with AB- and ABC-stacking. Considering an air/graphene/dielectric-water structure, the optical coefficients for those graphene systems are examined and compared. The universal optical conductance sigma(N)(0)=N pi e(2)/(2h) for N layer graphene systems in the visible region is verified. For N 3 layer graphene, the mini-gap induced absorption edges can be observed in odd layers AB-stacked multilayer graphene, where the number and position of the absorption edges are decided by the layers number N. Meanwhile, we can observe the optical absorption windows for those graphene systems in the infrared to terahertz bandwidth (0.2-150 THz). The absorption window is induced by different transition energies required for inter- and intra-band optical absorption channels. We find that the depth and width of the absorption window can be tuned not only via varying temperature and electron density but also by changing the number of graphene layers and the stacking order. These theoretical findings demonstrate that mono- and multi-layer graphene systems can be applied as frequency tunable optoelectronic devices working in infrared to terahertz bandwidth. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.588
Times cited: 7
DOI: 10.1016/j.optcom.2014.04.079
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“Integer and half-integer quantum Hall effect in silicene: Influence of an external electric field and impurities”. Shakouri K, Vasilopoulos P, Vargiamidis V, Peeters FM, Physical review : B : condensed matter and materials physics 90, 235423 (2014). http://doi.org/10.1103/PhysRevB.90.235423
Abstract: The influence of silicene's strong spin-orbit interaction and of an external electric field E-z on the transport coefficients are investigated in the presence of a perpendicular magnetic field B. For finite E-z the spin and valley degeneracy of the Landau levels is lifted and leads to additional plateaus in the Hall conductivity, at half-integer values of 4e(2)/h, due to spin intra-Landau-level transitions that are absent in graphene. These plateaus are more sensitive to disorder and thermal broadening than the main plateaus, occurring at integral values of 4e(2)/h, when the Fermi level passes through the Landau levels. We also evaluate the Hall and longitudinal resistivities and critically contrast the results with those for graphene on a substrate.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 32
DOI: 10.1103/PhysRevB.90.235423
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“The interband optical absorption in silicon quantum wells : application of the 30-band k . p model”. Čukarić, NA, Tadić, MZ, Partoens B, Peeters FM, Applied physics letters 104, 242103 (2014). http://doi.org/10.1063/1.4884122
Abstract: The interband optical absorption in Si/SiO2 quantum wells is calculated as function of the well width (W) and the evolution from an indirect to a direct gap material as function of the well width is investigated. In order to compute the electron states in the conduction band, the 30-band k . p model is employed, whereas the 6-band Luttinger-Kohn model is used for the hole states. We found that the effective direct band gap in the quantum well agrees very well with the W-2 scaling result of the single-band model. The interband matrix elements for linear polarized light oscillate with the quantum well width, which agrees qualitatively with a single band calculation. Our theoretical results indicate that the absorption can be maximized by a proper choice of the well width. However, the obtained absorption coefficients are at least an order of magnitude smaller than for a typical direct semiconductor even for a well width of 2 nm. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 1
DOI: 10.1063/1.4884122
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“Interplay between snake and quantum edge states in a graphene Hall bar with a pn-junction”. Milovanović, SP, Masir MR, Peeters FM, Applied physics letters 105, 123507 (2014). http://doi.org/10.1063/1.4896769
Abstract: The magneto- and Hall resistance of a locally gated cross shaped graphene Hall bar is calculated. The edge of the top gate is placed diagonally across the center of the Hall cross. Four-probe resistance is calculated using the Landauer-Büttiker formalism, while the transmission coefficients are obtained using the non-equilibrium Green's function approach. The interplay between transport due to edge channels and snake states is investigated. When two edge channels are occupied, we predict oscillations in the Hall and the bend resistance as function of the magnetic field, which are a consequence of quantum interference between the occupied snake states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 18
DOI: 10.1063/1.4896769
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“Luminescence, patterned metallic regions, and photon-mediated electronic changes in single-sided fluorinated graphene sheets”. Walter AL, Sahin H, Jeon KJ, Bostwick A, Horzum S, Koch R, Speck F, Ostler M, Nagel P, Merz M, Schupler S, Moreschini L, Chang YJ, Seyller T, Peeters FM, Horn K, Rotenberg E;, ACS nano 8, 7801 (2014). http://doi.org/10.1021/nn501163c
Abstract: Single-sided fluorination has been predicted to open an electronic band gap in graphene and to exhibit unique electronic and magnetic properties; however, this has not been substantiated by experimental reports. Our comprehensive experimental and theoretical study of this material on a SiC(0001) substrate shows that single-sided fluorographene exhibits two phases, a stable one with a band gap of similar to 6 eV and a metastable one, induced by UV irradiation, with a band gap of similar to 2.5 eV. The metastable structure, which reverts to the stable “ground-state” phase upon annealing under emission of blue light, in our view is induced by defect states, based on the observation of a nondispersive electronic state at the top of the valence band, not unlike that found in organic molecular layers. Our structural data show that the stable C2F ground state has a “boat” structure, in agreement with our X-ray magnetic circular dichroism data, which show the absence of an ordered magnetic phase. A high flux of UV or X-ray photons removes the fluorine atoms, demonstrating the possibility of lithographically patterning conducting regions into an otherwise semiconducting 2D material.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 13.942
Times cited: 23
DOI: 10.1021/nn501163c
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“Magnetic electron focusing and tuning of the electron current with a pn-junction”. Milovanović, SP, Masir MR, Peeters FM, Journal of applied physics 115, 043719 (2014). http://doi.org/10.1063/1.4863403
Abstract: Transverse magnetic focusing properties of graphene using a ballistic four terminal structure are investigated. The electric response is obtained using the semiclassical billiard model. The transmission exhibits pronounced peaks as a consequence of skipping orbits at the edge of the structure. When we add a pn-junction between the two probes, snake states along the pn-interface appear. Injected electrons are guided by the pn-interface to one of the leads depending on the value of the applied magnetic field. Oscillations in the resistance are found depending on the amount of particles that end up in each lead.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 21
DOI: 10.1063/1.4863403
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“Magnetic particles confined in a modulated channel : structural transitions tunable by tilting a magnetic field”. Galván Moya JE, Lucena D, Ferreira WP, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 89, 032309 (2014). http://doi.org/10.1103/PhysRevE.89.032309
Abstract: The ground state of colloidal magnetic particles in a modulated channel are investigated as a function of the tilt angle of an applied magnetic field. The particles are confined by a parabolic potential in the transversal direction while in the axial direction a periodic substrate potential is present. By using Monte Carlo simulations, we construct a phase diagram for the different crystal structures as a function of the magnetic field orientation, strength of the modulated potential, and the commensurability factor of the system. Interestingly, we found first-and second-order phase transitions between different crystal structures, which can be manipulated by the orientation of the external magnetic field. A reentrant behavior is found between two-and four-chain configurations, with continuous second-order transitions. Novel configurations are found consisting of frozen solitons of defects. By changing the orientation and/or strength of the magnetic field and/or the strength and periodicity of the substrate potential, the system transits through different phases.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 11
DOI: 10.1103/PhysRevE.89.032309
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“Majorana fermion states and fractional flux periodicity in mesoscopic d-wave superconducting loops with spin-orbit interaction”. Zha G-Q, Covaci L, Peeters FM, Zhou S-P, Physical review : B : condensed matter and materials physics 90, 014522 (2014). http://doi.org/10.1103/PhysRevB.90.014522
Abstract: We numerically investigate the spin-orbit (SO) coupling effect on the magnetic flux evolution of energy and supercurrent in mesoscopic d-wave superconducting loops by solving the spin-generalized Bogoliubov-de Gennes equations self-consistently. It is found that the energy spectrum splits when the SO interaction is involved and the Majorana zero mode can be realized in the [100] edges of square systems for an appropriate SO coupling strength. Superconducting phase transitions appear when the energy gap closes, accompanied by energy jumps between different energy parabolas in the ground state, which provides a possible mechanism to support fractional flux periodicity of supercurrent. Moreover, in the case of rectangular loops with SO coupling, the jumps of the ground-state energy gradually disappear by increasing the ratio of length to height of the sample, and a paramagnetic response with opposite direction of the screening current around zero flux value can occur in such systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.90.014522
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“Mechanical and thermal properties of h-MX2 (M = Cr, Mo, W, X = O, S, Se, Te) monolayers : a comparative study”. Çakir D, Peeters FM, Sevik C, Applied physics letters 104, 203110 (2014). http://doi.org/10.1063/1.4879543
Abstract: Using density functional theory, we obtain the mechanical and thermal properties of MX2 monolayers (where M = Cr, Mo, W and X = O, S, Se, Te). The C-centered phonon frequencies (i.e., A(1), A(2)'', E ', and E ''), relative frequency values of A(1), and E ' modes, and mechanical properties (i.e., elastic constants, Young modulus, and Poisson's ratio) display a strong dependence on the type of metal and chalcogenide atoms. In each chalcogenide (metal) group, transition-metal dichalcogenides (TMDCs) with W (O) atom are found to be much stiffer. Consistent with their stability, the thermal expansion of lattice constants for TMDCs with O (Te) is much slower (faster). Furthermore, in a heterostructure of these materials, the difference of the thermal expansion of lattice constants between the individual components becomes quite tiny over the whole temperature range. The calculated mechanical and thermal properties show that TMDCs are promising materials for heterostructures. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 130
DOI: 10.1063/1.4879543
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“Membrane amplitude and triaxial stress in twisted bilayer graphene deciphered using first-principles directed elasticity theory and scanning tunneling microscopy”. Neek-Amal M, Xu P, Qi D, Thibado PM, Nyakiti LO, Wheeler VD, Myers-Ward RL, Eddy CR, Gaskill DK, Peeters FM, Physical review : B : condensed matter and materials physics 90, 064101 (2014). http://doi.org/10.1103/PhysRevB.90.064101
Abstract: Twisted graphene layers produce a moire pattern (MP) structure with a predetermined wavelength for a given twist angle. However, predicting the membrane corrugation amplitude for any angle other than pure AB-stacked or AA-stacked graphene is impossible using first-principles density functional theory (DFT) due to the large supercell. Here, within elasticity theory, we define the MP structure as the minimum-energy configuration, thereby leaving the height amplitude as the only unknown parameter. The latter is determined from DFT calculations for AB-and AA-stacked bilayer graphene in order to eliminate all fitting parameters. Excellent agreement with scanning tunneling microscopy results across multiple substrates is reported as a function of twist angle.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 12
DOI: 10.1103/PhysRevB.90.064101
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“Monolayer behaviour in bulk ReS2 due to electronic and vibrational decoupling”. Tongay S, Sahin H, Ko C, Luce A, Fan W, Liu K, Zhou J, Huang YS, Ho CH, Yan J, Ogletree DF, Aloni S, Ji J, Li S, Li J, Peeters FM, Wu J;, Nature communications 5, 3252 (2014). http://doi.org/10.1038/ncomms4252
Abstract: Semiconducting transition metal dichalcogenides consist of monolayers held together by weak forces where the layers are electronically and vibrationally coupled. Isolated monolayers show changes in electronic structure and lattice vibration energies, including a transition from indirect to direct bandgap. Here we present a new member of the family, rhenium disulphide (ReS2), where such variation is absent and bulk behaves as electronically and vibrationally decoupled monolayers stacked together. From bulk to monolayers, ReS2 remains direct bandgap and its Raman spectrum shows no dependence on the number of layers. Interlayer decoupling is further demonstrated by the insensitivity of the optical absorption and Raman spectrum to interlayer distance modulated by hydrostatic pressure. Theoretical calculations attribute the decoupling to Peierls distortion of the 1T structure of ReS2, which prevents ordered stacking and minimizes the interlayer overlap of wavefunctions. Such vanishing interlayer coupling enables probing of two-dimensional-like systems without the need for monolayers.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 12.124
Times cited: 806
DOI: 10.1038/ncomms4252
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“Monolayers of MoS2 as an oxidation protective nanocoating material”. Sen HS, Sahin H, Peeters FM, Durgun E, Journal of applied physics 116, 083508 (2014). http://doi.org/10.1063/1.4893790
Abstract: First-principle calculations are employed to investigate the interaction of oxygen with ideal and defective MoS2 monolayers. Our calculations show that while oxygen atoms are strongly bound on top of sulfur atoms, the oxygen molecule only weakly interacts with the surface. The penetration of oxygen atoms and molecules through a defect-free MoS2 monolayer is prevented by a very high diffusion barrier indicating that MoS2 can serve as a protective layer for oxidation. The analysis is extended to WS2 and similar coating characteristics are obtained. Our calculations indicate that ideal and continuous MoS2 and WS2 monolayers can improve the oxidation and corrosion-resistance of the covered surface and can be considered as an efficient nanocoating material. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 52
DOI: 10.1063/1.4893790
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“Multilayer graphene, Moire patterns, grain boundaries and defects identified by scanning tunneling microscopy on the m-plane, non-polar surface of SiC”. Xu P, Qi D, Schoelz JK, Thompson J, Thibado PM, Wheeler VD, Nyakiti LO, Myers-Ward RL, Eddy CR, Gaskill DK, Neek-Amal M, Peeters FM;, Carbon 80, 75 (2014). http://doi.org/10.1016/j.carbon.2014.08.028
Abstract: Epitaxial graphene is grown on a non-polar n(+) 6H-SiC m-plane substrate and studied using atomic scale scanning tunneling microscopy. Multilayer graphene is found throughout the surface and exhibits rotational disorder. Moire patterns of different spatial periodicities are found, and we found that as the wavelength increases, so does the amplitude of the modulations. This relationship reveals information about the interplay between the energy required to bend graphene and the interaction energy, i.e. van der Waals energy, with the graphene layer below. Our experiments are supported by theoretical calculations which predict that the membrane topographical amplitude scales with the Moire pattern wavelength, L as L-1 + alpha L-2. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 6.337
Times cited: 14
DOI: 10.1016/j.carbon.2014.08.028
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“Nanofilms as effectively multiband superconductors: Intraband-pairing approximation and Ginzburg-Landau theory”. Shanenko AA, Vagov A, Peeters FM, Aguiar JA, Physica: B : condensed matter 455, 3 (2014). http://doi.org/10.1016/j.physb.2014.06.032
Abstract: It is well-known that the Ginzburg-Landau (GL) theory is a reliable and powerful theoretical tool to investigate the magnetic response of a superconducting state. However, in its standard form, this approach is not applicable to atomically uniform nano-thin superconducting films which are effective multiband superconductors. Here we discuss a relevant generalization of the GL theory, focusing on the underlying intraband-pairing approximation. (C) 2014 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.386
Times cited: 1
DOI: 10.1016/j.physb.2014.06.032
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“Nonlinear response to electric field in extended Hubbard models”. Esfahani DN, Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 90, 205121 (2014). http://doi.org/10.1103/PhysRevB.90.205121
Abstract: The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various nonlinear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the fidelity susceptibility of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time scales as long as the ground-state fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating phase, a dissipative regime, or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 3
DOI: 10.1103/PhysRevB.90.205121
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“Numerical solution of the time dependent Ginzburg-Landau equations for mixed (d plus s)-wave superconductors”. Goncalves WC, Sardella E, Becerra VF, Milošević, MV, Peeters FM, Journal of mathematical physics 55, 041501 (2014). http://doi.org/10.1063/1.4870874
Abstract: The time-dependent Ginzburg-Landau formalism for (d + s)-wave superconductors and their representation using auxiliary fields is investigated. By using the link variable method, we then develop suitable discretization of these equations. Numerical simulations are carried out for a mesoscopic superconductor in a homogeneous perpendicular magnetic field which revealed peculiar vortex states. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.077
Times cited: 6
DOI: 10.1063/1.4870874
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“Orbital magnetic moments in insulating Dirac systems : impact on magnetotransport in graphene van der Waals heterostructures”. Grujić, MM, Tadić, MZ, Peeters FM, Physical review : B : condensed matter and materials physics 90, 205408 (2014). http://doi.org/10.1103/PhysRevB.90.205408
Abstract: In honeycomb Dirac systems with broken inversion symmetry, orbital magnetic moments coupled to the valley degree of freedom arise due to the topology of the band structure, leading to valley-selective optical dichroism. On the other hand, in Dirac systems with prominent spin-orbit coupling, similar orbital magnetic moments emerge as well. These moments are coupled to spin, but otherwise have the same functional form as the moments stemming from spatial inversion breaking. After reviewing the basic properties of these moments, which are relevant for a whole set of newly discovered materials, such as silicene and germanene, we study the particular impact that these moments have on graphene nanoengineered barriers with artificially enhanced spin-orbit coupling. We examine transmission properties of such barriers in the presence of a magnetic field. The orbital moments are found to manifest in transport characteristics through spin-dependent transmission and conductance, making them directly accessible in experiments. Moreover, the Zeeman-type effects appear without explicitly incorporating the Zeeman term in the models, i.e., by using minimal coupling and Peierls substitution in continuum and the tight-binding methods, respectively. We find that a quasiclassical view is able to explain all the observed phenomena.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 5
DOI: 10.1103/PhysRevB.90.205408
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“Oscillating spin-orbit interaction as a source of spin-polarized wavepackets in two-terminal nanoscale devices”. Szaszko-Bogar V, Foeldi P, Peeters FM, Journal of physics : condensed matter 26, 135302 (2014). http://doi.org/10.1088/953-8984/26/13/135302
Abstract: Ballistic transport through nanoscale devices with time-dependent Rashba-type spin- orbit interaction (SOI) can lead to spin-polarized wavepackets that appear even for completely unpolarized input. The SOI that oscillates in a finite domain generates density and spin polarization fluctuations that leave the region as propagating waves. In particular, spin polarization has space and time dependence even in regions without SOI. Our results are based on an analytical solution of the time-dependent Schrodinger equation. The relevant Floquet quasi-energies that are obtained appear in the energy spectrum of both the transmitted and the reflected waves.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
DOI: 10.1088/953-8984/26/13/135302
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“Parametric amplification of vortex-antivortex pair generation in a Josephson junction”. Berdiyorov GR, Milošević, MV, Savel'ev S, Kusmartsev F, Peeters FM, Physical review : B : condensed matter and materials physics 90, 134505 (2014). http://doi.org/10.1103/PhysRevB.90.134505
Abstract: Using advanced three-dimensional simulations, we show that an Abrikosov vortex, trapped inside a cavity perpendicular to an artificial Josephson junction, can serve as a very efficient source for generation of Josephson vortex-antivortex pairs in the presence of the applied electric current. In such a case, the nucleation rate of the pairs can be tuned in a broad range by an out-of-plane ac magnetic field in a broad range of frequencies. This parametrically amplified vortex-antivortex nucleation can be considered as a macroscopic analog of the dynamic Casimir effect, where fluxon pairs mimic the photons and the ac magnetic field plays the role of the oscillating mirrors. The emerging vortex pairs in our system can be detected by the pronounced features in the measured voltage characteristics, or through the emitted electromagnetic radiation, and exhibit resonant dynamics with respect to the frequency of the applied magnetic field. Reported tunability of the Josephson oscillations can be useful for developing high-frequency emission devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 22
DOI: 10.1103/PhysRevB.90.134505
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“Plasmon and coupled plasmon-phonon modes in graphene in the presence of a driving electric field”. Zhao CX, Xu W, Dong HM, Peeters FM, Physical review : B : condensed matter and materials physics 89, 195447 (2014). http://doi.org/10.1103/PhysRevB.89.195447
Abstract: We present a theoretical study of the plasmon and coupled plasmon-phonon modes induced by intraband electron-electron interaction in graphene in the presence of driving dc electric field. We find that the electric field dependence of these collective excitation modes in graphene differs significantly from that in a conventional two-dimensional electron gas with a parabolic energy spectrum. This is due mainly to the fact that graphene has a linear energy spectrum and the Fermi velocity of electrons in graphene is much larger than the drift velocity of electrons. The obtained results demonstrate that the plasmon and coupled plasmon-phonon modes in graphene can be tuned by applying not only the gate voltage but also the source-to-drain field. The manipulation of plasmon and coupled plasmon-phonon modes by source-to-drain voltage can let graphene be more conveniently applied as an advanced plasmonic material.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.89.195447
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“Preface”. Aguiar JA, Roa-Rojas J, Parra Vargas CA, Landinez Tellez DA, Corredor Bohorquez LT, Shanenko A, Jardim RF, Peeters F, Physica: B : condensed matter 455, 1 (2014). http://doi.org/10.1016/j.physb.2014.05.013
Keywords: Editorial; Condensed Matter Theory (CMT)
Impact Factor: 1.386
DOI: 10.1016/j.physb.2014.05.013
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“Quantum rotor in nanostructured superconductors”. Lin S-H, Milošević, MV, Covaci L, Janko B, Peeters FM, Scientific reports 4, 4542 (2014). http://doi.org/10.1038/srep04542
Abstract: Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.259
Times cited: 4
DOI: 10.1038/srep04542
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“Reply to “Comment on 'Vortices induced in a superconducting loop by asymmetric kinetic inductance and their detection in transport measurements' ””. Berdiyorov GR, Milošević, MV, Peeters FM, Physical review : B : condensed matter and materials physics 90, 056502 (2014). http://doi.org/10.1103/PhysRevB.90.056502
Abstract: Our calculations, within known limitations of Ginzburg-Landau theory, are fully correct and valid for transport phenomena in asymmetric mesoscopic superconductors, deep in the superconducting state. We deemed the experiments of Burlakov et al. [JETP Lett. 86, 517 (2007)] relevant and important to mention in the general context of our paper since the observed shifts in the oscillations of different quantities are qualitatively similar, even though those measurements are performed close to the superconducting-normal state transition in the so-called Little-Parks regime.
Keywords: Editorial; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PhysRevB.90.056502
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“Role of atomic vacancies and boundary conditions on ballistic thermal transport in graphene nanoribbons”. Scuracchio P, Costamagna, Peeters FM, Dobry A, Physical review : B : condensed matter and materials physics 90, 035429 (2014). http://doi.org/10.1103/PhysRevB.90.035429
Abstract: Quantum thermal transport in armchair and zigzag graphene nanoribbons is investigated in the presence of single atomic vacancies and subject to different boundary conditions. We start with a full comparison of the phonon polarizations and energy dispersions as given by a fifth-nearest-neighbor force-constant model (5NNFCM) and by elasticity theory of continuum membranes (ETCM). For free-edge ribbons, we discuss the behavior of an additional acoustic edge-localized flexural mode, known as fourth acoustic branch (4ZA), which has a small gap when it is obtained by the 5NNFCM. Then, we show that ribbons with supported edges have a sample-size dependent energy gap in the phonon spectrum which is particularly large for in-plane modes. Irrespective to the calculation method and the boundary condition, the dependence of the energy gap for the low-energy optical phonon modes against the ribbon width W is found to be proportional to 1/W for in-plane, and 1/W-2 for out-of-plane phonon modes. Using the 5NNFCM, the ballistic thermal conductance and its contributions from every single phonon mode are then obtained by the nonequilibrium Green's function technique. We found that, while edge and central localized single atomic vacancies do not affect the low-energy transmission function of in-plane phonon modes, they reduce considerably the contributions of the flexural modes. On the other hand, in-plane modes contributions are strongly dependent on the boundary conditions and at low temperatures can be highly reduced in supported-edge samples. These findings could open a route to engineer graphene based devices where it is possible to discriminate the relative contribution of polarized phonons and to tune the thermal transport on the nanoscale.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 20
DOI: 10.1103/PhysRevB.90.035429
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“Self-assembly of Janus particles confined in a channel”. Sobrino Fernandez M, Misko VR, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 89, 022306 (2014). http://doi.org/10.1103/PhysRevE.89.022306
Abstract: Janus particles present an important class of building blocks for directional assembly. These are compartmentalized colloids with two different hemispheres. Here, we consider a two-dimensional model of Janus disks consisting of a hydrophobic semicircle and an electro-negatively charged one. Placed in a solution, the hydrophobic sides will attract each other while the charged sides will give rise to a repulsive force. Using molecular dynamics simulations, we study the morphology of these particles when confined in a channel-like environment using a one dimensional harmonic confinement potential. The interest to this system is first of all due to the fact that it could serve as a simple model for membrane formation. Indeed, the recently synthesized new class of artificial amphiphiles, known as Janus dendrimers, were shown to self-assemble in bilayer structures mimicking biological membranes. In turn, Janus particles that combine the amphiphilicity and colloidal rigidity serve as a good model for Janus dendrimers. A variety of ordered membrane-like morphologies are found consisting of single and multiple chain configurations with different orientations of the particles with respect to each other that we summarize in a phase diagram.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 11
DOI: 10.1103/PhysRevE.89.022306
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“Self-organization of highly symmetric nanoassemblies : a matter of competition”. Galván-Moya JE, Altantzis T, Nelissen K, Peeters FM, Grzelczak M, Liz-Marán LM, Bals S, Van Tendeloo G, ACS nano 8, 3869 (2014). http://doi.org/10.1021/nn500715d
Abstract: The properties and applications of metallic nanoparticles are inseparably connected not only to their detailed morphology and composition but also to their structural configuration and mutual interactions. As a result, the assemblies often have superior properties as compared to individual nanoparticles. Although it has been reported that nanoparticles can form highly symmetric clusters, if the configuration can be predicted as a function of the synthesis parameters, more targeted and accurate synthesis will be possible. We present here a theoretical model that accurately predicts the structure and configuration of self-assembled gold nanoclusters. The validity of the model is verified using quantitative experimental data extracted from electron tomography 3D reconstructions of different assemblies. The present theoretical model is generic and can in principle be used for different types of nanoparticles, providing a very wide window of potential applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 13.942
Times cited: 34
DOI: 10.1021/nn500715d
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“Self-organized platinum nanoparticles on freestanding graphene”. Xu P, Dong L, Neek-Amal M, Ackerman ML, Yu J, Barber SD, Schoelz JK, Qi D, Xu F, Thibado PM, Peeters FM;, ACS nano 8, 2697 (2014). http://doi.org/10.1021/nn406394f
Abstract: Freestanding graphene membranes were successfully functionalized with platinum nanoparticles (Pt NPs). High-resolution transmission electron microscopy revealed a homogeneous distribution of single-crystal Pt NPs that tend to exhibit a preferred orientation. Unexpectedly, the NPs were also found to be partially exposed to the vacuum with the top Pt surface raised above the graphene substrate, as deduced from atomic-scale scanning tunneling microscopy images and detailed molecular dynamics simulations. Local strain accumulation during the growth process is thought to be the origin of the NP self-organization. These findings are expected to shape future approaches in developing Pt NP catalysts for fuel cells as well as NP-functionalized graphene-based high-performance electronics.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 13.942
Times cited: 38
DOI: 10.1021/nn406394f
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“Single-file and normal diffusion of magnetic colloids in modulated channels”. Lucena D, Galván Moya JE, Ferreira WP, Peeters FM, Physical review : E : statistical, nonlinear, and soft matter physics 89, 032306 (2014). http://doi.org/10.1103/PhysRevE.89.032306
Abstract: Diffusive properties of interacting magnetic dipoles confined in a parabolic narrow channel and in the presence of a periodic modulated (corrugated) potential along the unconfined direction are studied using Brownian dynamics simulations. We compare our simulation results with the analytical result for the effective diffusion coefficient of a single particle by Festa and d'Agliano [Physica A 90, 229 (1978)] and show the importance of interparticle interaction on the diffusion process. We present results for the diffusion of magnetic dipoles as a function of linear density, strength of the periodic modulation and commensurability factor.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.366
Times cited: 5
DOI: 10.1103/PhysRevE.89.032306
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“Spin- and valley-dependent commensurability oscillations and electric-field-induced quantum Hall plateaux in periodically modulated silicene”. Shakouri K, Vasilopoulos P, Vargiamidis V, Hai G-Q, Peeters FM, Applied physics letters 104, 213109 (2014). http://doi.org/10.1063/1.4878509
Abstract: We study the commensurability oscillations in silicene subject to a perpendicular electric field E-z, a weak magnetic field B, and a weak periodic potential V = V-0 cos(Cy); C = 2 pi/a(0) with a(0) its period. The field E-z and/or the modulation lift the spin degeneracy of the Landau levels and lead to spin and valley resolved Weiss oscillations. The spin resolution is maximal when the field E-z is replaced by a periodic one E-z = E-0 cos(Dy); D = 2 pi/b(0), while the valley one is maximal for b(0) = a(0). In certain ranges of B values, the current is fully spin or valley polarized. Additional quantum Hall conductivity plateaux arise due to spin and valley intra-Landau-level transitions. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 16
DOI: 10.1063/1.4878509
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“Spin- and valley-dependent magnetotransport in periodically modulated silicene”. Shakouri K, Vasilopoulos P, Vargiamidis V, Peeters FM, Physical review : B : condensed matter and materials physics 90, 125444 (2014). http://doi.org/10.1103/PhysRevB.90.125444
Abstract: The low-energy physics of silicene is described by Dirac fermions with a strong spin-orbit interaction and its band structure can be controlled by an external perpendicular electric field E-z. We investigate the commensurability oscillations in silicene modulated by a weak periodic potential V = V-0 cos(2 pi y/a(0)) with a(0) as its period, in the presence of a perpendicular magnetic field B and of a weak sinusoidal electric field E-z = E-0 cos(2 pi y/b(0)), where b(0) is its period. We show that the spin and valley degeneracy of the Landau levels is lifted, due to the modulation, and that the interplay between the strong spin-orbit interaction and the potential and electric field modulations can result in spin- and valley-resolved magnetotransport. At very weak magnetic fields the commensurability oscillations induced by a weak potential modulation can exhibit a beating pattern depending on the strength of the homogenous electric field Ez but this is not the case when only Ez is modulated. The Hall conductivity plateaus acquire a step structure, due to spin and valley intra-Landau-level transitions, that is absent in unmodulated silicene. The results are critically contrasted with those for graphene and the two-dimensional electron gas.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 31
DOI: 10.1103/PhysRevB.90.125444
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