|
“Magnetic traps for excitons in GaAs/AlxGa1-xAs quantum wells”. Freire JAK, Peeters FM, Matulis A, Freire VN, Farias GA, , 503 (2001)
Keywords: P1 Proceeding; Condensed Matter Theory (CMT)
|
|
|
“Magneto-exciton in single and coupled type II quantum dots”. Janssens KL, Partoens B, Peeters FM, Physica status solidi: A: applied research 190, 571 (2002). http://doi.org/10.1002/1521-396X(200204)190:2<571::AID-PSSA571>3.0.CO;2-K
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1002/1521-396X(200204)190:2<571::AID-PSSA571>3.0.CO;2-K
|
|
|
“Magneto-optical spectrum of a quantum dot”. Geerinckx F, Peeters FM, Wen X, Devreese JT, (1991)
Keywords: P3 Proceeding; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
|
|
|
“Melting properties of two-dimensional multi-species colloidal systems in a parabolic trap”. Yang W, Nelissen K, Kong MH, Li YT, Tian YM, European physical journal : B : condensed matter and complex systems 83, 499 (2011). http://doi.org/10.1140/epjb/e2011-20595-9
Abstract: The angular and radial melting properties of two-dimensional classical systems consisting of different types of particles confined in a parabolic trap are studied through modified Monte Carlo simulations. A universal behavior of the angular melting process is found, which occurs in multiple steps due to shell depended melting temperatures. The melting sequence of the different shells is determined by two major factors: (1) the confinement strength which each shell is subjected to, and (2) the specific structure of each shell. Further, a continuous radial disordering of the particle types forming a single circular shell is found and analyzed. This phenomenon has never been observed before in two-dimensional mono-dispersive systems. This continuous radial disordering results from the high energy barrier between different particle types in multi-species systems.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 2
DOI: 10.1140/epjb/e2011-20595-9
|
|
|
“Moore's law: new playground for quantum physics”. van Rossum M, Schoenmaker W, Magnus W, de Meyer K, Croitoru MD, Gladilin VN, Fomin VM, Devreese JT, Physica status solidi: B: basic research 237, 426 (2003). http://doi.org/10.1002/pssb.200301788
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
Impact Factor: 1.674
Times cited: 2
DOI: 10.1002/pssb.200301788
|
|
|
“Nanotube field and one-dimensional fluctuations of C60 molecules in carbon nanotubes”. Michel KH, Verberck B, Nikolaev AV, European physical journal : B : condensed matter and complex systems 48, 113 (2005). http://doi.org/10.1140/epjb/e2005-00378-9
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 25
DOI: 10.1140/epjb/e2005-00378-9
|
|
|
“Nonlinear transport of the Wigner crystal in symmetric and asymmetric FET-like structures : nonlinear transport of the Wigner crystal on superfluid He-4 in quasi-one-dimensional channels with symmetric and asymmetric constrictions”. Vasylenko AA, Misko VR, European physical journal : B : condensed matter and complex systems 88, 105 (2015). http://doi.org/10.1140/epjb/e2015-60217-0
Abstract: When floating on a two-dimensional surface of superfluid He-4, electrons arrange themselves in two-dimensional crystalline structure known as Wigner crystal. In channels, the boundaries interfere the crystalline order and in case of very narrow channels one observes a quasi-one-dimensional (quasi-1D) Wigner crystal formed by just a few rows of electrons and, ultimately, one row in the “quantum wire” regime. Recently, the “quantum wire” regime was accessed experimentally [D.G. Rees, H. Totsuji, K. Kono, Phys. Rev. Lett. 108, 176801 (2012)] resulting in unusual transport phenomena such as, e.g., oscillations in the electron conductance. Using molecular dynamics simulations, we study the nonlinear transport of electrons in channels with various types of constrictions: single and multiple symmetric and asymmetric geometrical constrictions with varying width and length, and saddle-point-type potentials with varying gate voltage. In particular, we analyze the average particle velocity of the particles and the corresponding electron current versus the driving force or the gate voltage. We have revealed a significant difference in the dynamics for long and short constrictions: The oscillations of the average velocity of the particles for the systems with short constrictions exhibit a clear correlation with the transitions between the states with different numbers of rows of particles; on the other hand, for the systems with longer constrictions these oscillations are suppressed. The obtained results qualitatively agree with the experimental observations. Next, we propose a FET-like structure that consists of a channel with asymmetric constrictions. We show that applying a transverse bias results either in increase of the average particle velocity or in its suppression thus allowing a flexible control tool over the electron transport. The advantage of the asymmetric FET is that it does not have a gate and it allows an easy control of relatively large electron flow. Furthermore, the asymmetric device can be used for rectification of an ac-driven electron flow. Our results bring important insights into the dynamics of electrons floating on the surface of superfluid He-4 in channels with constrictions and allow the effective control over the electron transport.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
DOI: 10.1140/epjb/e2015-60217-0
|
|
|
“Optically detected magnetophonon resonance in GaAs-GaAlAs heterojunctions”. Barnes DJ, Nicholas RJ, Watts M, Peeters FM, Wu XG, Devreese JT, Langerak CJ, Singleton J, Harris JJ, Foxon CT, (1991)
Keywords: P3 Proceeding; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
|
|
|
“Optoelectronic properties of ABC-stacked trilayer graphene”. Xiao YM, Xu W, Zhang YY, Peeters FM, Physica status solidi: B: basic research 250, 86 (2013). http://doi.org/10.1002/pssb.201248169
Abstract: We present a theoretical study on the optoelectronic properties of ABC-stacked trilayer graphene (TLG). The optical conductance and light transmittance are evaluated through using the energy-balance equation derived from the Boltzmann equation for an air/graphene/dielectric-wafer system in the presence of linearly polarized radiation field. The results obtained from two band structure models are examined and compared. For short wavelength radiation, the universal optical conductance sigma(0) = 3e(2)/(4h) can be obtained. Importantly, there exists an optical absorption window in the radiation wavelength range 10-200 mu m, which is induced by different transition energies required for inter- and intra-band optical absorption channels. As a result, we find that the position and width of this window depend sensitively on temperature and carrier density of the system, especially the lower frequency edge. There is a small characteristic absorption peak at about 82 mu m where the largest interband transition states exist in the ABC-stacked TLG model, in contrast to the relatively smooth curves in a simplified model. These theoretical results indicate that TLG has some interesting and important physical properties which can be utilized to realize infrared or THz optoelectronic devices.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 6
DOI: 10.1002/pssb.201248169
|
|
|
“Orientational mode coupling, diffuse scattering, and the order-disorder phase transition in solid C60”. Michel KH, Copley JRD, Zeitschrift für Physik: B: condensed matter and quanta 103, 369 (1997)
Keywords: A3 Journal article; Condensed Matter Theory (CMT)
Times cited: 21
|
|
|
“Polarity-dependent vortex pinning and spontaneous vortex-antivortex structures in superconductor/ferromagnet hybrids”. Bending SJ, Milošević MV, Moshchalkov VV Springer, Berlin, page 299 (2010).
Keywords: H1 Book chapter; Condensed Matter Theory (CMT)
|
|
|
“Positive and negative charged excitons in a semiconductor quantum well”. Riva C, Peeters FM, Varga K, Physica status solidi: B: basic research 227, 397 (2001). http://doi.org/10.1002/1521-3951(200110)227:2<397::AID-PSSB397>3.0.CO;2-X
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 5
DOI: 10.1002/1521-3951(200110)227:2<397::AID-PSSB397>3.0.CO;2-X
|
|
|
“Quantum charge density fluctuations and the γ-&alpha, phase transition in Ce”. Nikolaev AV, Michel KH, European physical journal : B : condensed matter and complex systems 9, 619 (1999). http://doi.org/10.1007/s100510050806
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 19
DOI: 10.1007/s100510050806
|
|
|
“Rigid-plane phonons in layered crystals”. Michel KH, Verberck B, Physica status solidi: B: basic research 249, 2604 (2012). http://doi.org/10.1002/pssb.201200119
Abstract: The determination of the layer number ${\cal N}$ in nanoscale thin layered crystals is a challenging problem of technological relevance. In addition to innovative experimental techniques, a thorough knowledge of the underlying lattice dynamics is required. Starting from phenomenological atomic interaction potentials we have carried out an analytical study of the low-frequency optical phonon dispersions in layered crystals. At the gamma point of the two-dimensional Brillouin zone the optical phonon frequencies correspond to rigid-plane shearing and compression modes. We have investigated graphene multilayers (GML) and hexagonal boron-nitride multilayers (BNML). The frequencies show a characteristic dependence on ${\cal N}$. The results which are represented in the form of fan diagrams are very similar for both materials. Due to charge neutrality within layers Coulomb forces play no role, only van der Waals forces between nearest neighbor layers are relevant. The theoretical results agree with recent low-frequency Raman results on rigid-layer modes [Tan et al., Nature Mater. 11, 294 (2012)] in GML and double-resonant Raman scattering data on rigid-layer compression modes [Herziger et al., Phys. Rev. B 85, 235447 (2012)] in GML. (C) 2012 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 1
DOI: 10.1002/pssb.201200119
|
|
|
“Scheme for coherently quenching resonant current in a three-level quantum dot energy level mixer”. Austing DG, Payette C, Nair SV, Yu G, Gupta JA, Partoens B, Amaha S, Tarucha S, Physica status solidi: C: conferences and critical reviews 6, 940 (2009). http://doi.org/10.1002/pssc.200880584
Abstract: We outline a scheme to create a dark state by three-level mixing that is potentially a useful tool for quantum coherent transport. Magnetic-field-induced intra-dot level mixing can lead to rich quantum superposition phenomena between three approaching single-particle states in a quantum dot when probed by the ground state of an adjacent weakly coupled quantum dot in the single-electron resonant tunnelling regime. The mixing relies on non-negligible anharmonicity and anisotropy in confining potentials of realistic quantum dots. Anti-crossing and transfer of strengths between resonances can be understood with a simple coherent level mixing model. Superposition can lead to the formation of a dark state by complete cancellation of an otherwise strong resonance. This is an all-electrical analogue of coherent population trapping seen in three-level-systems from quantum and atom optics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
DOI: 10.1002/pssc.200880584
|
|
|
“Strong-coupling limit for one-dimensional polarons in a finite box”. Vansant P, Smondyrev MA, Peeters FM, Devreese JT, Zeitschrift für Physik: B: condensed matter and quanta 99, 345 (1996). http://doi.org/10.1007/s002570050047
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Theory of quantum systems and complex systems
Times cited: 1
DOI: 10.1007/s002570050047
|
|
|
“Theoretical phonon dispersions in monolayers and multilayers of hexagonal boron-nitride”. Michel KH, Verberck B, Physica status solidi: B: basic research 246, 2802 (2009). http://doi.org/10.1002/pssb.200982307
Abstract: Starting from an empirical force constant model of valence interactions and calculating by Ewald's method the electrostatic force constants, we derive the dynamical matrix for a monolayer and for multilayer systems of hexagonal boron nitride (h-BN). Solution of the secular problem leads to the corresponding phonon dispersion relations. The interplay between valence forces and Coulomb forces is discussed. A comparison with previous results on graphene and graphene multilayers is made. Our spectra on the h-BN monolayer are rather similar to previous ab initio theory results. Comparison is also made with Raman and infrared experimental results.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 10
DOI: 10.1002/pssb.200982307
|
|
|
“Theory of phonon dispersions and piezoelectricity in multilayers of hexagonal boron-nitride”. Michel KH, Verberck B, Physica status solidi: B: basic research 248, 2720 (2011). http://doi.org/10.1002/pssb.201100084
Abstract: Taking into account covalent, Coulomb and van der Waals interactions, we construct the dynamical matrix and calculate the phonon dispersion relations for multilayer crystals of hexagonal boron-nitride. Coulomb interactions account for a strong overbending of optical phonons. Applying and extending Born's long-wave theory to the case of multilayer crystals, we calculate the piezoelectric stress constant equation image as a function of the number of layers equation image. In agreement with group theory, we find that equation image for equation image even; for an uneven number equation image of layers we obtain equation image, i.e. the piezoelectric constant decreases as equation image.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 13
DOI: 10.1002/pssb.201100084
|
|
|
“Theory of the elastic constants of graphite and graphene”. Michel KH, Verberck B, Physica status solidi: B: basic research 245, 2177 (2008). http://doi.org/10.1002/pssb.200879604
Abstract: Born's long wave method is used to study the elastic properties of graphite and graphene. Starting from an empirical force constant model derived from full inplane phonon dispersions of graphite [Mohr et al., Phys. Rev. B 76, 035439 (2007)] we calculate the tension coefficients of graphene. Extending the model by interplanar interactions, we calculate the elastic constants of graphite. The agreement of our theoretical values with inelastic x-ray scattering results on elastic constants of graphite [Bosak et al., Phys. Rev. B 75, 153408 (2007)] is very satisfactory.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 47
DOI: 10.1002/pssb.200879604
|
|
|
“Tubular fullerenes inside carbon nanotubes : optimal molecular orientation versus tube radius”. Verberck B, Tarakina NV, European physical journal : B : condensed matter and complex systems 80, 355 (2011). http://doi.org/10.1140/epjb/e2011-10952-1
Abstract: We present an investigation of the orientations and positions of tubular fullerene molecules (C90, ..., C200) encapsulated in single-walled carbon nanotubes (SWCNT), a series of so-called fullerene nanopeapods. We find that increasing the tube radius leads to the following succession of energetically stable regimes: (1) lying molecules positioned on the tube's long axis; (2) tilted molecules on the tube's long axis; and (3) lying molecules shifted away from the tube's long axis. As opposed to C70 and C80 molecules encapsulated in a SWCNT, standing orientations do not develop. Our results are relevant for the possible application of molecular-orientation-dependent electronic properties of fullerene nanopeapods, and also for the interpretation of future experiments on double-walled carbon nanotube formation by annealing fullerene peapod systems.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 10
DOI: 10.1140/epjb/e2011-10952-1
|
|
|
“Tunneling through a combined magnetic-potential barrier”. Papp G, Peeters FM, Physica status solidi: B: basic research 225, 433 (2001)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
|
|
|
“Effect of ordered array of magnetic dots on the dynamics of Josephson vortices in stacked SNS Josephson junctions under DC and AC current”. Berdiyorov GR, Savel'ev S, Kusmartsev FV, Peeters FM, European physical journal : B : condensed matter and complex systems 88, 286 (2015). http://doi.org/10.1140/epjb/e2015-60628-9
Abstract: We use the anisotropic time-dependent Ginzburg-Landau theory to investigate the effect of a square array of out-of-plane magnetic dots on the dynamics of Josephson vortices (fluxons) in artificial stacks of superconducting-normal-superconducting (SNS) Josephson junctions in the presence of external DC and AC currents. Periodic pinning due to the magnetic dots distorts the triangular lattice of fluxons and results in the appearance of commensurability features in the current-voltage characteristics of the system. For the larger values of the magnetization, additional peaks appear in the voltage-time characteristics of the system due to the creation and annihilation of vortex-antivortex pairs. Peculiar changes in the response of the system to the applied current is found resulting in a “superradiant” vortex-flow state at large current values, where a rectangular lattice of moving vortices is formed. Synchronizing the motion of fluxons by adding a small ac component to the biasing dc current is realized. However, we found that synchronization becomes difficult for large magnetization of the dots due to the formation of vortex-antivortex pairs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 1
DOI: 10.1140/epjb/e2015-60628-9
|
|
|
“Theory of thermal expansion in 2D crystals”. Michel KH, Costamagna, Peeters FM, Physica status solidi: B: basic research 252, 2433 (2015). http://doi.org/10.1002/pssb.201552286
Abstract: The thermal expansion alpha(T) in layered crystals is of fundamental and technological interest. As suggested by I. M. Lifshitz in 1952, in thin solid films (crystalline membranes) a negative contribution to alpha(T) is due to anharmonic couplings between in-plane stretching modes and out-of-plane bending (flexural modes). Genuine in-plane anharmonicities give a positive contribution to alpha(T). The competition between these two effects can lead to a change of sign (crossover) from a negative value of alpha(T) in a temperature (T) range T <= T-alpha to a positive value of alpha(T) for T > T-alpha in layered crystals. Here, we present an analytical lattice dynamical theory of these phenomena for a two-dimensional (2D) hexagonal crystal. We start from a Hamiltonian that comprises anharmonic terms of third and fourth order in the lattice displacements. The in-plane and out-of-plane contributions to the thermal expansion are studied as functions of T for crystals of different sizes. Besides, renormalization of the flexural mode frequencies plays a crucial role in determining the crossover temperature T-alpha. Numerical examples are given for graphene where the anharmonic couplings are determined from experiments. The theory is applicable to other layer crystals wherever the anharmonic couplings are known. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 21
DOI: 10.1002/pssb.201552286
|
|
|
“Wave fronts and packets in 1D models of different meta-materials : graphene, left-handed media and transmission line”. Matulis A, Zarenia M, Peeters FM, Physica status solidi: B: basic research 252, 2330 (2015). http://doi.org/10.1002/pssb.201552023
Abstract: A comparative study is made of the propagation of wave packets and fronts in three different meta-media, i.e. graphene, left-handed media (LHM) and transmission lines, using one-dimensional models. It is shown that a potential step in graphene influences only the frequency of the electronic wave, i.e., the particular spectrum branch (electron or hole) to which the wave belongs to, while the envelop function (the wave front or packet form) remains unchanged. Although the model for a vacuum and LHM interface is similar to that of the potential step in graphene, the solutions are quite different due to differences in the chirality of the waves. Comparing the propagation of wave fronts and packets in a standard transmission line and its meta-analog we demonstrate that the propagating packets in the meta-line are much more deformed as compared to the standard one, including broadening, asymmetry and even the appearance of fast moving precursors. This influence is seen not only in the case of packets with steep fronts but in soft Gaussian packets as well.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 1
DOI: 10.1002/pssb.201552023
|
|
|
“Finite-temperature Wigner solid and other phases of ripplonic polarons on a helium film”. Klimin SN, Tempère J, Misko VR, Wouters M, European physical journal : B : condensed matter and complex systems 89, 172 (2016). http://doi.org/10.1140/EPJB/E2016-70149-8
Abstract: Electrons on liquid helium can form different phases depending on density, and temperature. Also the electron-ripplon coupling strength influences the phase diagram, through the formation of so-called “ripplonic polarons”, that change how electrons are localized, and that shifts the transition between the Wigner solid and the liquid phase. We use an all-coupling, finite-temperature variational method to study the formation of a ripplopolaron Wigner solid on a liquid helium film for different regimes of the electron-ripplon coupling strength. In addition to the three known phases of the ripplopolaron system (electron Wigner solid, polaron Wigner solid, and electron fluid), we define and identify a fourth distinct phase, the ripplopolaron liquid. We analyse the transitions between these four phases and calculate the corresponding phase diagrams. This reveals a reentrant melting of the electron solid as a function of temperature. The calculated regions of existence of the Wigner solid are in agreement with recent experimental data.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 1.461
Times cited: 1
DOI: 10.1140/EPJB/E2016-70149-8
|
|
|
“Static flexural modes and piezoelectricity in 2D and layered crystals”. Michel KH, Neek-Amal M, Peeters FM, Physica status solidi: B: basic research 253, 2311 (2016). http://doi.org/10.1002/PSSB.201600226
Abstract: Piezo- and flexoelectricity are manifestations of electromechanical coupling in solids with potential applications in nanoscale materials. Naumov etal. [Phys. Rev. Lett. 102, 217601 (2009)] have shown by first principles calculations that a monolayer BN sheet becomes macroscopically polarized in-plane when in a corrugated state. Here, we investigate the interplay of layer corrugation and in-plane polarization by atomistic lattice dynamics. We treat the coupling between static flexural modes and in-plane atomic ion displacements as an anharmonic effect, similar to the membrane effect that is at the origin of negative thermal expansion in layered crystals. We have derived analytical expressions for the corrugation-induced static in-plane strains and the optical displacements with the resulting polarization response functions. Beyond h-BN, the theory applies to transition metal dichalcogenides and dioxides. Numerical calculations show that the effects are considerably stronger for 2D h-BN than for 2H-MoS2.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 5
DOI: 10.1002/PSSB.201600226
|
|
|
“Relaxation of quantum dots in a magnetic field at finite bias -Charge, spin, and heat currents”. Vanherck J, Schulenborg J, Saptsov RB, Splettstoesser J, Wegewijs MR, Physica status solidi: B: basic research 254, Unsp 1600614 (2017). http://doi.org/10.1002/PSSB.201600614
Abstract: <script type='text/javascript'>document.write(unpmarked('We perform a detailed study of the effect of finite bias and magnetic field on the tunneling-induced decay of the state of a quantum dot by applying a recently discovered general duality [Phys. Rev. B 93, 81411 (2016)]. This duality provides deep physical insight into the decay dynamics of electronic open quantum systems with strong Coulomb interaction. It associates the amplitudes of decay eigenmodes of the actual system to the eigenmodes of a so-called dual system with attractive interaction. Thereby, it predicts many surprising features in the transient transport and its dependence on experimental control parameters: the attractive interaction of the dual model shows up as sharp features in the amplitudes of measurable time-dependent currents through the actual repulsive system. In particular, for interacting quantum dots, the time-dependent heat current exhibits a decay mode that dissipates the interaction energy and that is tied to the fermion parity of the system. We show that its decay amplitude has an unexpected gate-voltage dependence that is robust up to sizable bias voltages and then bifurcates, reflecting that the Coulomb blockade is lifted in the dual system. Furthermore, combining our duality relation with the known Iche-duality, we derive new symmetry properties of the decay rates as a function of magnetic field and gate voltage. Finally, we quantify charge- and spin-mode mixing due to the magnetic field using a single mixing parameter.'));
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.674
Times cited: 4
DOI: 10.1002/PSSB.201600614
|
|
|
“Accurate description of the van der Waals interaction of an electron-positron pair with the surface of a topological insulator”. Saniz R, Vercauteren S, Lamoen D, Partoens B, Barbiellini B, Journal of physics : conference series 505, 012002 (2014). http://doi.org/10.1088/1742-6596/505/1/012002
Abstract: Positrons can be trapped in localized states at the surface of a material, and thus quite selectively interact with core or valence surface electrons. Hence, advanced surface positron spectroscopy techniques can present the ideal tools to study a topological insulator, where surface states play a fundamental role. We analyze the problem of a positron at a TI surface, assuming that it is a weakly physisorbed positronium (Ps) atom. To determine if the surface of interest in a material can sustain such a physisorption, an accurate description of the underlying van der Waals (vdW) interaction is essential. We have developed a first-principles parameterfree method, based on the density functional theory, to extract key parameters determining the vdW interaction potential between a Ps atom and the surface of a given material. The method has been successfully applied to quartz and preliminary results on Bi2Te2Se indicate the existence of a positron surface state. We discuss the robustness of our predictions versus the most relevant approximations involved in our approach.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Times cited: 2
DOI: 10.1088/1742-6596/505/1/012002
|
|
|
“The ageing effect in topological insulators : evolution of the surface electronic structure of Bi2Se3 upon K adsorption”. Park K, De Beule C, Partoens B, New journal of physics 15, 113031 (2013). http://doi.org/10.1088/1367-2630/15/11/113031
Abstract: Topological insulators (TIs) have attracted a lot of interest in recent years due to their topologically protected surface states, as well as exotic proximity-induced phenomena and device applications for TI heterostructures. Since the first experimental studies of TIs, angle-resolved photoemission spectra (ARPES) showed that the electronic structure of the topological surface states significantly changes as a function of time after cleavage. The origin and underlying mechanism of this ageing effect are still under debate, despite its importance. Here we investigate the evolution of the surface Dirac cone for Bi2Se3 films upon asymmetric potassium (K) adsorption, using density-functional theory and a tight-binding model. We find that the K adatoms induce short-ranged downward band bending within 2-3 nm from the surface, due to charge transfer from the adatoms to the TI. These findings are in contrast to earlier proposals in the literature, that propose a long-ranged downward band bending up to 15 nm from the surface. Furthermore, as the charge transfer increases, we find that a new Dirac cone, localized slightly deeper into the TI than the original one, appears at the K-adsorbed surface, originating from strong Rashba-split conduction-band states. Our results suggest possible reinterpretations of experiments because the new Dirac cone might have been observed in ARPES measurements instead of the original one that appears immediately after cleavage. Our findings are consistent with ARPES data and provide insight into building TI-heterostructure devices by varying the band-bending potential or film thickness.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.786
Times cited: 45
DOI: 10.1088/1367-2630/15/11/113031
|
|
|
“Analysis of pattern formation in systems with competing range interactions”. Zhao HJ, Misko VR, Peeters FM, New journal of physics 14, 063032 (2012). http://doi.org/10.1088/1367-2630/14/6/063032
Abstract: We analyzed pattern formation and identified various morphologies in a system of particles interacting through a non-monotonic potential with a competing range interaction characterized by a repulsive core (r < r(c)) and an attractive tail (r > r(c)), using molecular-dynamics simulations. Depending on parameters, the interaction potential models the inter-particle interaction in various physical systems ranging from atoms, molecules and colloids to vortices in low kappa type-II superconductors and in recently discovered 'type-1.5' superconductors. We constructed a 'morphology diagram' in the plane 'critical radius r(c)-density n' and proposed a new approach to characterizing the different types of patterns. Namely, we elaborated a set of quantitative criteria in order to identify the different pattern types, using the radial distribution function (RDF), the local density function and the occupation factor.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.786
Times cited: 45
DOI: 10.1088/1367-2630/14/6/063032
|
|