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“Influence of finite size effects on exchange anisotropy in oxidized Co nanocluster assembled films”. Dobrynin AN, Ievlev DN, Hendrich C, Temst K, Lievens P, Hörmann U, Verbeeck J, Van Tendeloo G, Vantomme A, Physical review : B : condensed matter and materials physics 73, 245416 (2006). http://doi.org/10.1103/PhysRevB.73.245416
Abstract: We compare the magnetic properties of Co cluster assembled films with different degrees of oxidation. Clusters with grain size (2.3 +/- 0.7) nm are produced in a laser vaporization cluster source and soft-landed in ultrahigh vacuum conditions, forming highly porous nanogranular films. After exposure to air for different periods of time, the Co clusters oxidize and the sample may be considered as a thin antiferromagnetic Co oxide matrix containing ferromagnetic Co clusters. Magnetization measurements were performed in a temperature range from 300 down to 5 K, at applied magnetic fields up to 30 kOe. The exchange bias value at 5 K for the strongly oxidized sample is 4.8 kOe against the value of 0.75 kOe for the less oxidized sample. The mean values of the thicknesses of the Co oxide layers are estimated to be 0.6 and 0.3 nm for the more and less oxidized sample, respectively. We propose a method of measuring the exchange bias inducing temperature, i.e., the temperature at which exchange anisotropy is established. We determined the mean inducing temperatures for both samples, which are 55 and 25 K, respectively, for the more and less oxidized samples. Both temperatures are well below the bulk CoO Neel temperature of 292 K. A low value of the inducing temperature of the Co oxide layer is a consequence of its subnanometer thickness, while a large exchange bias value is a consequence of different dimensionality of Co clusters and Co oxide matrix.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.73.245416
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“Erratum : First-principles study of possible shallow donors in ZnAl2O4 spinel [Phys. Rev. B 87, 174101 (2013)]”. Dixit H, Tandon N, Cottenier S, Saniz R, Lamoen D, Partoens B, Physical review : B : condensed matter and materials physics 88, 059905 (2013). http://doi.org/10.1103/PhysRevB.88.059905
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PhysRevB.88.059905
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“First-principles study of possible shallow donors in ZnAl2O4 spinel”. Dixit H, Tandon N, Cottenier S, Saniz R, Lamoen D, Partoens B, Physical review : B : condensed matter and materials physics 87, 174101 (2013). http://doi.org/10.1103/PhysRevB.87.174101
Abstract: ZnAl2O4 (gahnite) is a ceramic which is considered a possible transparent conducting oxide (TCO) due to its wide band gap and transparency for UV. Defects play an important role in controlling the conductivity of a TCO material along with the dopant, which is the main source of conductivity in an otherwise insulating oxide. A comprehensive first-principles density functional theory study for point defects in ZnAl2O4 spinel is presented using the Heyd, Scuseria, and Ernzerhof hybrid functional (HSE06) to overcome the band gap problem. We have investigated the formation energies of intrinsic defects which include the Zn, Al, and O vacancy and the antisite defects: Zn at the Al site (ZnAl) and Al at the Zn site (AlZn). The antisite defect AlZn has the lowest formation energy and acts as a shallow donor, indicating possible n-type conductivity in ZnAl2O4 spinel by Al doping.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 50
DOI: 10.1103/PhysRevB.87.174101
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“Interfacial spin glass state and exchange bias in manganite bilayers with competing magnetic orders”. Ding JF, Lebedev OI, Turner S, Tian YF, Hu WJ, Seo JW, Panagopoulos C, Prellier W, Van Tendeloo G, Wu T, Physical review : B : condensed matter and materials physics 87, 054428 (2013). http://doi.org/10.1103/PhysRevB.87.054428
Abstract: The magnetic properties of manganite bilayers composed of G-type antiferromagnetic (AFM) SrMnO3 and double-exchange ferromagnetic (FM) La0.7Sr0.3MnO3 are studied. A spin-glass state is observed as a result of competing magnetic orders and spin frustration at the La0.7Sr0.3MnO3/SrMnO3 interface. The dependence of the irreversible temperature on the cooling magnetic field follows the Almeida-Thouless line. Although an ideal G-type AFM SrMnO3 is featured with a compensated spin configuration, the bilayers exhibit exchange bias below the spin glass freezing temperature, which is much lower than the Néel temperature of SMO, indicating that the exchange bias is strongly correlated with the spin glass state. The results indicate that the spin frustration that originates from the competition between the AFM super-exchange and the FM double-exchange interactions can induce a strong magnetic anisotropy at the La0.7Sr0.3MnO3/SrMnO3 interface.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 98
DOI: 10.1103/PhysRevB.87.054428
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“Gate controlled Aharonov-Bohm-type oscillations from single neutral excitons in quantum rings”. Ding F, Akopian N, Li B, Perinetti U, Govorov A, Peeters FM, Bufon CC, Deneke C, Chen YH, Rastelli A, Schmidt OG, Zwiller V, Physical review : B : condensed matter and materials physics 82, 8 (2010). http://doi.org/10.1103/PhysRevB.82.075309
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 58
DOI: 10.1103/PhysRevB.82.075309
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“Hysteresis in mesoscopic superconducting disks: the Bean-Livingston barrier”. Deo PS, Schweigert VA, Peeters FM, Physical review : B : condensed matter and materials physics 59, 6039 (1999). http://doi.org/10.1103/PhysRevB.59.6039
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 59
DOI: 10.1103/PhysRevB.59.6039
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“Conductance quantization in a periodically modulated quantum channel: backscattering and mode mixing”. Deo PS, Gupta BC, Jayannavar AM, Peeters FM, Physical review : B : condensed matter and materials physics 58, 10784 (1998). http://doi.org/10.1103/PhysRevB.58.10784
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 12
DOI: 10.1103/PhysRevB.58.10784
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“Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene”. Dell'Anna L, Perali A, Covaci L, Neilson D, Physical review : B : condensed matter and materials physics 92, 220502 (2015). http://doi.org/10.1103/PhysRevB.92.220502
Abstract: Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity v(F) smaller. We demonstrate that with current experimental techniques, the reduction in vF can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.92.220502
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“Bound states and lifetime of an electron on a bulk helium surface”. Degani MH, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 72, 125408 (2005). http://doi.org/10.1103/PhysRevB.72.125408
Abstract: We propose an effective potential for an excess electron near the helium liquid-vapor interface that takes into account the diffuseness of the liquid-vapor interface and the classical image potential. The splitting of the first two excited states of the excess electron bound to the helium liquid-vapor interface as a function of an external constant electric field applied perpendicular to the interface is in excellent agreement with recent experiments. The effect of a parallel magnetic field on the energy levels are calculated. Single-electron tunneling of the electron out of its surface state is studied as a function of the electric field applied to the system. We found that the tunneling time has a linear dependence on the electric field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.72.125408
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“Braess paradox at the mesoscopic scale”. de Sousa AA, Chaves A, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 88, 245417 (2013). http://doi.org/10.1103/PhysRevB.88.245417
Abstract: We theoretically demonstrate that the transport inefficiency recently found experimentally for branched-out mesoscopic networks can also be observed in a quantum ring of finite width with an attached central horizontal branch. This is done by investigating the time evolution of an electron wave packet in such a system. Our numerical results show that the conductivity of the ring does not necessary improve if one adds an extra channel. This ensures that there exists a quantum analog of the Braess paradox, originating from quantum scattering and interference.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 17
DOI: 10.1103/PhysRevB.88.245417
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“Topological confinement in trilayer graphene”. de Sena SHR, Pereira JM, Peeters FM, Farias GA, Physical review : B : condensed matter and materials physics 89, 035420 (2014). http://doi.org/10.1103/PhysRevB.89.035420
Abstract: We calculate the spectrum of states that are localized at the interface between two regions of opposite bias in trilayer graphene (TLG). These potential profiles, also known as potential kinks, have been predicted to support two different branches of localized states for the case of bilayer graphene, and show similarities to the surface states of topological insulators. On the other hand, we found that ABC stacked TLG exhibits three different unidimensional branches of states in each valley that are confined to the kink interface. They have the property E(k(y)) = -E(-k(y)) when belonging to the same valley and E-K(k(y)) = -E-K' (-k(y)). A kink-antikink potential profile opens a gap in the spectrum of these one-dimensional states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.89.035420
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“Anisotropic cluster model for the short-range order in Cu1-xPdx-type alloys”. De Meulenaere P, Rodewald M, Van Tendeloo G, Physical review : B : condensed matter and materials physics 57, 11132 (1998). http://doi.org/10.1103/PhysRevB.57.11132
Abstract: The split diffuse maxima around the {110} and {100} positions in the diffraction pattern of short-range-ordered Cu1-xPdx alloys (x=0.10...0.60) are attributed to small atomic clusters, being part of the underlying fee lattice. By analyzing the reciprocal space geometry, our cluster method identifies two prominent cluster types: the tetrahedron of nearest neighbors and a linear three-points cluster along the [110] directions. Since both cluster types contain different information on the same nearest-neighbor correlations, local anisotropy has to be assumed. It is shown that the three interatomic pair interactions within these basic clusters are sufficient to generate the spot splitting in the diffraction pattern. A ground-state analysis with these interactions reproduces the results of the anisotropic next-nearest-neighbor Ising model.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PhysRevB.57.11132
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“Oxygen vacancies effects in a-IGZO : formation mechanisms, hysteresis, and negative bias stress effects”. de de Meux AJ, Bhoolokam A, Pourtois G, Genoe J, Heremans P, Physica status solidi : A : applications and materials science 214, 1600889 (2017). http://doi.org/10.1002/PSSA.201600889
Abstract: The amorphous oxide semiconductor Indium-Gallium-Zinc-Oxide (a-IGZO) has gained a large technological relevance as a semiconductor for thin-film transistors in active-matrix displays. Yet, major questions remain unanswered regarding the atomic origin of threshold voltage control, doping level, hysteresis, negative bias stress (NBS), and negative bias illumination stress (NBIS). We undertake a systematic study of the effects of oxygen vacancies on the properties of a-IGZO by relating experimental observations to microscopic insights gained from first-principle simulations. It is found that the amorphous nature of the semiconductor allows unusually large atomic relaxations. In some cases, oxygen vacancies are found to behave as perfect shallow donors without the formation of structural defects. Once structural defects are formed, their transition states can vary upon charge and discharge cycles. We associate this phenomenon to a possible presence of hysteresis in the transfer curve of the devices. Under NBS, the creation of oxygen vacancies becomes energetically very stable, hence thermodynamically very likely. This generation process is correlated with the occurrence of the negative bias stress instabilities observed in a-IGZO transistors. While oxygen vacancies can therefore be related to NBS and hysteresis, it appears unlikely from our results that they are direct causes of NBIS, contrary to common belief.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.775
Times cited: 8
DOI: 10.1002/PSSA.201600889
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“Gapless interface states at the junction between two topological insulators”. De Beule C, Partoens B, Physical review : B : condensed matter and materials physics 87, 115113 (2013). http://doi.org/10.1103/PhysRevB.87.115113
Abstract: We consider a junction between two topological insulators and calculate the properties of the interface states with an effective low-energy Hamiltonian for topological insulators with a single cone on the surface. This system bears a close resemblance to bilayer graphene, as both result from the hybridization of Dirac cones. We find gapless interface states not only when the helicity directions of the topological surface states are oppositely oriented, but they can also exist if they are equally oriented. Furthermore, we find that the existence of the interface states can be understood from the closing of the bulk gap when the helicity changes orientation. Recently superluminal tachyonic excitations were also claimed to exist at the interface between topological insulators. However, here we show that these interface states do not exist. DOI: 10.1103/PhysRevB.87.115113
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.87.115113
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“Phase diagram for large two dimensional bipolarons in a magnetic field”. da Costa WB, Peeters FM, Physical review : B : condensed matter and materials physics 57, 10569 (1998). http://doi.org/10.1103/PhysRevB.57.10569
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.57.10569
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“Energy levels of bilayer graphene quantum dots”. da Costa DR, Zarenia M, Chaves A, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 92, 115437 (2015). http://doi.org/10.1103/PhysRevB.92.115437
Abstract: Within a tight binding approach we investigate the energy levels of hexagonal and triangular bilayer graphene (BLG) quantum dots (QDs) with zigzag and armchair edges. We study AA- and AB-(Bernal) stacked BLG QDs and obtain the energy levels in both the absence and the presence of a perpendicular electric field (i.e., biased BLG QDs). Our results show that the size dependence of the energy levels is different from that of monolayer graphene QDs. The energy spectrum of AB-stacked BLG QDs with zigzag edges exhibits edge states which spread out into the opened energy gap in the presence of a perpendicular electric field. We found that the behavior of these edges states is different for the hexagonal and triangular geometries. In the case of AA-stacked BLG QDs, the electron and hole energy levels cross each other in both cases of armchair and zigzag edges as the dot size or the applied bias increases.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.92.115437
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“Geometry and edge effects on the energy levels of graphene quantum rings : a comparison between tight-binding and simplified Dirac models”. da Costa DR, Chaves A, Zarenia M, Pereira JM, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 89, 075418 (2014). http://doi.org/10.1103/PhysRevB.89.075418
Abstract: We present a systematic study of the energy spectra of graphene quantum rings having different geometries and edge types in the presence of a perpendicular magnetic field. Results are obtained within the tight-binding (TB) and Dirac models and we discuss which features of the former can be recovered by using the approximations imposed by the latter. Energy levels of graphene quantum rings obtained by diagonalizing the TB Hamiltonian are demonstrated to be strongly dependent on the rings geometry and the microscopical structure of the edges. This makes it difficult to recover those spectra by the existing theories that are based on the continuum (Dirac) model. Nevertheless, our results show that both approaches (i.e., TB and Dirac model) may provide similar results, but only for very specific combinations of ring geometry and edge types. The results obtained by a simplified model describing an infinitely thin circular Dirac ring show good agreement with those obtained for hexagonal and rhombus armchair graphene rings within the TB model. Moreover, we show that the energy levels of a circular quantum ring with an infinite mass boundary condition obtained within the Dirac model agree with those for a ring defined by a ring-shaped staggered potential obtained within the TB model.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 56
DOI: 10.1103/PhysRevB.89.075418
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“Valley filtering using electrostatic potentials in bilayer graphene”. da Costa DR, Chaves A, Sena SHR, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 92, 045417 (2015). http://doi.org/10.1103/PhysRevB.92.045417
Abstract: Propagation of an electron wave packet through a quantum point contact (QPC) defined by electrostatic gates in bilayer graphene is investigated. The gates provide a bias between the layers, in order to produce an energy gap. If the gates on both sides of the contact produce the same bias, steps in the electron transmission probability are observed, as in the usual QPC. However, if the bias is inverted on one of the sides of the QPC, only electrons belonging to one of the Dirac valleys are allowed to pass, which provides a very efficient valley filtering.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 47
DOI: 10.1103/PhysRevB.92.045417
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“Wave-packet scattering on graphene edges in the presence of a pseudomagnetic field”. da Costa DR, Chaves A, Farias GA, Covaci L, Peeters FM, Physical review : B : condensed matter and materials physics 86, 115434 (2012). http://doi.org/10.1103/PhysRevB.86.115434
Abstract: The scattering of a Gaussian wave packet in armchair and zigzag graphene edges is theoretically investigated by numerically solving the time-dependent Schrodinger equation for the tight-binding model Hamiltonian. Our theory allows us to investigate scattering in reciprocal space, and depending on the type of graphene edge we observe scattering within the same valley, or between different valleys. In the presence of an external magnetic field, the well-known skipping orbits are observed. However, our results demonstrate that in the case of a pseudomagnetic field, induced by nonuniform strain, the scattering by an armchair edge results in a nonpropagating edge state.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 28
DOI: 10.1103/PhysRevB.86.115434
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“30-band k\cdot p model of electron and hole states in silicon quantum wells”. Čukarić, NA, Tadić, MZ, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 88, 205306 (2013). http://doi.org/10.1103/PhysRevB.88.205306
Abstract: We modeled the electron and hole states in Si/SiO2 quantum wells within a basis of standing waves using the 30-band k . p theory. The hard-wall confinement potential is assumed, and the influence of the peculiar band structure of bulk silicon on the quantum-well sub-bands is explored. Numerous spurious solutions in the conduction-band and valence-band energy spectra are found and are identified to be of two types: (1) spurious states which have large contributions of the bulk solutions with large wave vectors (the high-k spurious solutions) and (2) states which originate mainly from the spurious valley outside the Brillouin zone (the extravalley spurious solutions). An algorithm to remove all those nonphysical solutions from the electron and hole energy spectra is proposed. Furthermore, slow and oscillatory convergence of the hole energy levels with the number of basis functions is found and is explained by the peculiar band mixing and the confinement in the considered quantum well. We discovered that assuming the hard-wall potential leads to numerical instability of the hole states computation. Nonetheless, allowing the envelope functions to exponentially decay in a barrier of finite height is found to improve the accuracy of the computed hole states.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 10
DOI: 10.1103/PhysRevB.88.205306
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“Hole states in nanocups in a magnetic field”. Čukarić, N, Arsoski V, Tadić, M, Peeters FM, Physical review : B : condensed matter and materials physics 85, 235425 (2012). http://doi.org/10.1103/PhysRevB.85.235425
Abstract: The magnetic-field dependence of the hole states in a nanocup, which is composed of a ring (the nanocup rim) that surrounds a disk (the nanocup bottom), is obtained within the Luttinger-Kohn model for the unstrained GaAs/(Al,Ga) As and the strained (In,Ga) As/GaAs systems. Aharonov-Bohm oscillations due to angular momentum transitions of the hole ground state appear with periods that vary with the thickness of the disk. The strain in the (In, Ga) As/GaAs nanocup is sensitive to the disk thickness and favors the spatial localization of the heavy holes inside the disk. Therefore, the angular momentum transitions between the valence-band states disappear for much thinner disks than in the case of the unstrained GaAs/(Al, Ga) As nanocups. In both systems, the oscillations in the energy of the hole ground state are found to disappear for thinner inner layer than in the electron ground-state energy. This is due to the different confining potentials and the mixing between the heavy- and light-hole states. As a consequence, magnetization of the single hole is found to strongly depend on the bottom thickness of the strained (In, Ga) As/GaAs nanocup. Furthermore, we found that the strain can lead to a spatial separation of the electron and the hole, as in type-II band alignment, which is advantageous for the appearance of the excitonic Aharonov-Bohm effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.85.235425
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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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“Dependence of superconducting properties on the size and shape of a nanoscale superconductor: from nanowire to film”. Croitoru MD, Shanenko AA, Peeters FM, Physical review : B : condensed matter and materials physics 76, 024511 (2007). http://doi.org/10.1103/PhysRevB.76.024511
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 54
DOI: 10.1103/PhysRevB.76.024511
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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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“Electroluminescence spectra of an STM-tip-induced quantum dot”. Croitoru MD, Gladilin VN, Fomin VM, Devreese JT, Kemerink M, Koenraad PM, Sauthoff K, Wolter JH, Physical review : B : condensed matter and materials physics 68, 195307 (2003). http://doi.org/10.1103/PhysRevB.68.195307
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.68.195307
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“Peculiarities of the orbital effect in the Fulde-Ferrell-Larkin-Ovchinnikov state in quasi-one-dimensional superconductors”. Croitoru MD, Buzdin AI, Physical review : B : condensed matter and materials physics 89, 224506 (2014). http://doi.org/10.1103/PhysRevB.89.224506
Abstract: Using the quasiclassical formalism, we determine the low-temperature phase diagram of a quasi-one-dimensional superconductor, taking into account the interchain Josephson coupling and the paramagnetic spin splitting. We show that the anisotropy of the onset of superconductivity changes in the FFLO state as compared with the conventional superconducting phase. It can result in anomalous peaks in the field-direction dependence of the upper critical field when the magnetic field length equals to the FFLO period. This regime is characterized by the lock-in effect of the FFLO modulation wave vector, which is governed by the magnetic length. Furthermore, in the FFLO phase, the anisotropy of the upper critical field is inverted at T-1(**) = 0.5T(c0), where the orbital anisotropy disappears. We suggest that an experimental study of the anisotropy of the upper critical field can provide very reach information about the parameters of the FFLO phase in quasi-1D samples.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
DOI: 10.1103/PhysRevB.89.224506
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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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“Thermal rippling behavior of graphane”. Costamagna S, Neek-Amal M, Los JH, Peeters FM, Physical review : B : condensed matter and materials physics 86, 041408 (2012). http://doi.org/10.1103/PhysRevB.86.041408
Abstract: Thermal fluctuations of single layer hydrogenated graphene (graphane) are investigated using large scale atomistic simulations. By analyzing the mean square value of the height fluctuations < h(2)> and the height-height correlation function H(q) for different system sizes and temperatures, we show that hydrogenated graphene is an unrippled system in contrast to graphene. The height fluctuations are bounded, which is confirmed by a H(q) tending to a constant in the long wavelength limit instead of showing the characteristic scaling law q(4-eta)(eta similar or equal to 0.85) predicted by membrane theory. This unexpected behavior persists up to temperatures of at least 900 K and is a consequence of the fact that in graphane the thermal energy can be accommodated by in-plane bending modes, i.e., modes involving C-C-C bond angles in the buckled carbon layer, instead of leading to significant out-of-plane fluctuations that occur in graphene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 46
DOI: 10.1103/PhysRevB.86.041408
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“Graphene ribbons with a line of impurities: oOpening of a gap”. Costa Filho RN, Farias GA, Peeters FM, Physical review : B : condensed matter and materials physics 76, 193409 (2007). http://doi.org/10.1103/PhysRevB.76.193409
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 49
DOI: 10.1103/PhysRevB.76.193409
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“Conductance of a copper-nanotube bundle interface: impact of interface geometry and wave-function interference”. Compemolle S, Pourtois G, Sorée B, Magnus W, Chibotaru LF, Ceulemans A, Physical review : B : condensed matter and materials physics 77, 193406 (2008). http://doi.org/10.1103/PhysRevB.77.193406
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.77.193406
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