“Large magnetoresistance oscillations in mesoscopic superconductors due to current-excited moving vortices”. Berdiyorov GR, Milošević, MV, Latimer ML, Xiao ZL, Kwok WK, Peeters FM, Physical review letters 109, 057004 (2012). http://doi.org/10.1103/PhysRevLett.109.057004
Abstract: We show in the case of a superconducting Nb ladder that a mesoscopic superconductor typically exhibits magnetoresistance oscillations whose amplitude and temperature dependence are different from those stemming from the Little-Parks effect. We demonstrate that these large resistance oscillations (as well as the monotonic background on which they are superimposed) are due to current-excited moving vortices, where the applied current in competition with the oscillating Meissner currents imposes or removes the barriers for vortex motion in an increasing magnetic field. Because of the ever present current in transport measurements, this effect should be considered in parallel with the Little-Parks effect in low-critical temperature (T-c) samples, as well as with recently proposed thermal activation of dissipative vortex-antivortex pairs in high-T-c samples.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 65
DOI: 10.1103/PhysRevLett.109.057004
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“Magnetization measurements and Ginzburg-Landau simulations of micron-size \beta-tin samples : evidence for an unusual critical behavior of mesoscopic type-I superconductors”. Müller A, Milošević, MV, Dale SEC, Engbarth MA, Bending SJ, Physical review letters 109, 197003 (2012). http://doi.org/10.1103/PhysRevLett.109.197003
Abstract: We describe investigations of the largely unexplored field of mesoscopic type-I superconductors. Micromagnetometry and 3D Ginzburg-Landau simulations of our single crystal β-tin samples in this regime reveal size- and temperature-dependent supercritical fields whose behavior is radically different from the bulk critical field HcB. We find that complete suppression of the intermediate state in medium-size samples can result in a surprising reduction of the critical field significantly below HcB. We also reveal an evolution of the superconducting-to-normal phase transition from the expected irreversible first order at low temperatures through the previously unobserved reversible first-order to a second-order transition close to Tc, where the critical field can be many times larger than HcB. Finally, we have identified striking correlations between the mesoscopic Hc3 for nucleation of surface superconductivity and the thermodynamic Hc near Tc. All these observations are entirely unexpected in the conventional type-I picture.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 21
DOI: 10.1103/PhysRevLett.109.197003
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“Spin-orbit-mediated manipulation of heavy-hole spin qubits in gated semiconductor nanodevices”. Szumniak P, Bednarek S, Partoens B, Peeters FM, Physical review letters 109, 107201 (2012). http://doi.org/10.1103/PhysRevLett.109.107201
Abstract: A novel spintronic nanodevice is proposed that is able to manipulate the single heavy-hole spin state in a coherent manner. It can act as a single quantum logic gate. The heavy-hole spin transformations are realized by transporting the hole around closed loops defined by metal gates deposited on top of the nanodevice. The device exploits Dresselhaus spin-orbit interaction, which translates the spatial motion of the hole into a rotation of the spin. The proposed quantum gate operates on subnanosecond time scales and requires only the application of a weak static voltage which allows for addressing heavy-hole spin qubits individually. Our results are supported by quantum mechanical time-dependent calculations within the four-band Luttinger-Kohn model.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 41
DOI: 10.1103/PhysRevLett.109.107201
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“Unconventional vortex states in nanoscale superconductors due to shape-induced resonances in the inhomogeneous Cooper-pair condensate”. Zhang L-F, Covaci L, Milošević, MV, Berdiyorov GR, Peeters FM, Physical review letters 109, 107001 (2012). http://doi.org/10.1103/PhysRevLett.109.107001
Abstract: Vortex matter in mesoscopic superconductors is known to be strongly affected by the geometry of the sample. Here we show that in nanoscale superconductors with coherence length comparable to the Fermi wavelength the shape resonances of the order parameter results in an additional contribution to the quantum topological confinement-leading to unconventional vortex configurations. Our Bogoliubov-de Gennes calculations in a square geometry reveal a plethora of asymmetric, giant multivortex, and vortex-antivortex structures, stable over a wide range of parameters and which are very different from those predicted by the Ginzburg-Landau theory. These unconventional states are relevant for high-T-c nanograins, confined Bose-Einstein condensates, and graphene flakes with proximity-induced superconductivity.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 31
DOI: 10.1103/PhysRevLett.109.107001
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“Position-dependent effect of non-magnetic impurities on superconducting properties of nanowires”. Zhang L-F, Covaci L, Peeters FM, Europhysics letters 109, 17010 (2015). http://doi.org/10.1209/0295-5075/109/17010
Abstract: Anderson's theorem states that non-magnetic impurities do not change the bulk properties of conventional superconductors. However, as the dimensionality is reduced, the effect of impurities becomes more significant. Here we investigate superconducting nanowires with diameter comparable to the Fermi wavelength $\lambda_F$ (which is less than the superconducting coherence length) by using a microscopic description based on the Bogoliubov-de Gennes method. We find that: 1) impurities strongly affect the superconducting properties, 2) the effect is impurity position dependent, and 3) it exhibits opposite behavior for resonant and off-resonant wire widths. We show that this is due to the interplay between the shape resonances of the order parameter and the subband energy spectrum induced by the lateral quantum confinement. These effects can be used to manipulate the Josephson current, filter electrons by subband and investigate the symmetries of the superconducting subband gaps.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 7
DOI: 10.1209/0295-5075/109/17010
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“Strain controlled valley filtering in multi-terminal graphene structures”. Milovanović, SP, Peeters FM, Applied physics letters 109, 203108 (2016). http://doi.org/10.1063/1.4967977
Abstract: Valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by the deformation allows electrons from only one valley to transmit, and a current of electrons from a single valley is generated at the opposite side of the locally strained region. We show that valley filtering is most effective with bumps of a certain height and width. Despite the fact that the highest contribution to the polarized current comes from electrons from the lowest sub-band, contributions of other sub-bands are not negligible and can significantly enhance the output current. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 50
DOI: 10.1063/1.4967977
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“The wear of polished and glazed zirconia against enamel”. Janyavula S, Lawson N, Çakir D, Beck P, Ramp LC, Burgess JO, Journal Of Prosthetic Dentistry 109, 22 (2013). http://doi.org/10.1016/S0022-3913(13)60005-0
Abstract: Statement of problem. The wear of tooth structure opposing anatomically contoured zirconia crowns requires further investigation. Purpose. The purpose of this in vitro study was to measure the roughness and wear of polished, glazed, and polished then reglazed zirconia against human enamel antagonists and compare the measurements to those of veneering porcelain and natural enamel. Material and methods. Zirconia specimens were divided into polished, glazed, and polished then reglazed groups (n=8). A veneering porcelain (Ceramco3) and enamel were used as controls. The surface roughness of all pretest specimens was measured. Wear testing was performed in the newly designed Alabama wear testing device. The mesiobuccal cusps of extracted molars were standardized and used as antagonists. Three-dimensional (3D) scans of the specimens and antagonists were obtained at baseline and after 200 000 and 400 000 cycles with a profilometer. The baseline scans were superimposed on the posttesting scans to determine volumetric wear. Data were analyzed with a 1-way ANOVA and Tukey Honestly Significant Difference (HSD) post hoc tests (alpha=.05) Results. Surface roughness ranked in order of least rough to roughest was: polished zirconia, glazed zirconia, polished then reglazed zirconia, veneering porcelain, and enamel. For ceramic, there was no measureable loss on polished zirconia, moderate loss on the surface of enamel, and significant loss on glazed and polished then reglazed zirconia. The highest ceramic wear was exhibited by the veneering ceramic. For enamel antagonists, polished zirconia caused the least wear, and enamel caused moderate wear. Glazed and polished then reglazed zirconia showed significant opposing enamel wear, and veneering porcelain demonstrated the most. Conclusions. Within the limitations of the study, polished zirconia is wear-friendly to the opposing tooth. Glazed zirconia causes more material and antagonist wear than polished zirconia. The surface roughness of the zirconia aided in predicting the wear of the opposing dentition. (J Prosthet Dent 2013;109:22-29)
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.095
Times cited: 89
DOI: 10.1016/S0022-3913(13)60005-0
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“Charged vacancy in graphene : interplay between Landau levels and atomic collapse resonances”. Wang J, Zhao W-S, Hu Y, Filho RNC, Peeters FM, Physical review B 109, 104103 (2024). http://doi.org/10.1103/PHYSREVB.109.104103
Abstract: The interplay between a magnetic field and the Coulomb potential from a charged vacancy on the electron states in graphene is investigated within the tight-binding model. The Coulomb potential removes locally Landau level degeneracy, while the vacancy introduces a satellite level next to the normal Landau level. These satellite levels are found throughout the positive-energy region, but in the negative-energy region, they turn into atomic collapse resonances. Crossings between Landau levels with different angular quantum number m are found. Unlike the point impurity system in which an anticrossing occurs between Landau levels of the same m, in this work anticrossing is found between the normal Landau level and the vacancy-induced level. The atomic collapse resonance hybridizes with the Landau levels. The charge at which the lowest Landau level m = -1, N = 1 crosses E = 0 increases with enhancing magnetic field. A Landau level scaling anomaly occurs when the charge is larger than the critical charge beta 0.6 and this critical charge is independent of the magnetic field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.109.104103
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“Effects of intralayer correlations on electron-hole double-layer superfluidity”. Pascucci F, Conti S, Perali A, Tempère J, Neilson D, Physical review B 109, 094512 (2024). http://doi.org/10.1103/PHYSREVB.109.094512
Abstract: We investigate the intralayer correlations acting within the layers in a superfluid system of electron -hole spatially separated layers. In this system, superfluidity is predicted to be almost exclusively confined to the Bose-Einstein condensate (BEC) and crossover regimes where the electron -hole pairs are well localized. In this case, Hartree-Fock is an excellent approximation for the intralayer correlations. We find in the BEC regime that the effect of the intralayer correlations on superfluid properties is negligible but in the BCS-BEC crossover regime the superfluid gap is significantly weakened by the intralayer correlations. This is caused by the intralayer correlations boosting the number of low -energy particle -hole excitations that drive the screening. We further find that the intralayer correlations suppress the predicted phenomenon in which the average pair size passes through a minimum as the crossover regime is traversed.
Keywords: A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.109.094512
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“McMillan-Ginzburg-Landau theory of singularities and discommensurations in charge density wave states of transition metal dichalcogenides”. Moura VN, Chaves A, Peeters FM, Milošević, MV, Physical review B 109, 094507 (2024). http://doi.org/10.1103/PHYSREVB.109.094507
Abstract: The McMillan-Ginzburg-Landau (MGL) model for charge density waves (CDW) is employed in a systematic phenomenological study of the different phases that have been probed in recent experiments involving transition metal dichalcogenides. We implemented an efficient imaginary time evolution method to solve the MGL equations, which enabled us to investigate the role of different coupling parameters on the CDW patterns and to perform calculations with different energy functionals that lead to several experimentally observed singularities in the CDW phase profiles. In particular, by choosing the appropriate energy functionals, we were able to obtain phases that go beyond the well-known periodic phase slips (discommensurations), exhibiting also topological defects (i.e., vortex-antivortex pairs), domain walls where the CDW order parameter is suppressed, and even CDW with broken rotational symmetry. Finally, we briefly discuss the effect of these different CDW phases on the profile and critical temperature of the competing superconducting state.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.109.094507
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“Tailoring weak and metallic phases in a strong topological insulator by strain and disorder : conductance fluctuations signatures”. Shafiei M, Fazileh F, Peeters FM, Milošević, MV, Physical review B 109, 045129 (2024). http://doi.org/10.1103/PHYSREVB.109.045129
Abstract: Transport measurements are readily used to probe different phases in disordered topological insulators (TIs), where determining topological invariants explicitly is challenging. On that note, universal conductance fluctuations (UCF) theory asserts the conductance G for an ensemble has a Gaussian distribution, and that standard deviation 8G depends solely on the symmetries and dimensions of the system. Using a real-space tight -binding Hamiltonian on a system with Anderson disorder, we explore conductance fluctuations in a thin Bi2Se3 film and demonstrate the agreement of their behavior with UCF hypotheses. We further show that magnetic field applied out-of-plane breaks the time -reversal symmetry and transforms the system's Wigner-Dyson class from root symplectic to unitary, increasing 8G by 2. Finally, we reveal that while Bi2Se3 is a strong TI, weak TI and metallic phases can be stabilized in presence of strain and disorder, and detected by monitoring the conductance fluctuations.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PHYSREVB.109.045129
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“Charge transfer and polymer phases in AC60 (A=K, Rb, Cs) fullerides”. Nikolaev AV, Prassides K, Michel KH, The journal of chemical physics 108, 4912 (1998). http://doi.org/10.1063/1.475900
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.965
Times cited: 14
DOI: 10.1063/1.475900
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“Measurement of specimen thickness by phase change determination in TEM”. Croitoru MD, van Dyck D, Liu YZ, Zhang Z, Ultramicroscopy 108, 1616 (2008). http://doi.org/10.1016/j.ultramic.2008.06.002
Abstract: A non-destructive method for measuring the thickness of thin amorphous films composed of light elements has been developed. The method employs the statistics of the phase of the electron exit wave function. The accuracy of this method has been checked numerically by the multislice method and compared with that based on the mean inner potential.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 2
DOI: 10.1016/j.ultramic.2008.06.002
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“A simplified quantum mechanical model for nanowire transistors based on non-linear variational calculus”. Carrillo-Nuñez H, Magnus W, Peeters FM, Journal of applied physics 108, 063708 (2010). http://doi.org/10.1063/1.3476297
Abstract: A simplified quantum mechanical model is developed to investigate quantum transport features such as the electron concentration and the current flowing through a silicon nanowire metal-oxide-semiconductor field-effect transistor (MOSFET). In particular, the electron concentration is extracted from a self-consistent solution of the Schrödinger and Poisson equations as well as the ballistic Boltzmann equation which have been solved by exploiting a nonlinear variational principle within the framework of the generalized local density approximation. A suitable action functional has been minimized and details of the implementation and its numerical minimization are given. The current density and its related current-voltage characteristics are calculated from the one-dimensional ballistic steady-state Boltzmann transport equation which is solved analytically by using the method of characteristic curves. The straightforward implementation, the computational speed and the good qualitative behavior of the transport characteristics observed in our approach make it a promising simulation method for modeling quantum transport in nanowire MOSFETs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 7
DOI: 10.1063/1.3476297
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“Two-band superconductors : hidden criticality deep in the superconducting state”. Komendová, L, Chen Y, Shanenko AA, Milošević, MV, Peeters FM, Physical review letters 108, 207002 (2012). http://doi.org/10.1103/PhysRevLett.108.207002
Abstract: We show that two-band superconductors harbor hidden criticality deep in the superconducting state, stemming from the critical temperature of the weaker band taken as an independent system. For sufficiently small interband coupling gamma the coherence length of the weaker band exhibits a remarkable deviation from the conventional monotonic increase with temperature, namely, a pronounced peak close to the hidden critical point. The magnitude of the peak scales as proportional to gamma(-mu), with the Landau critical exponent mu = 1/3, the same as found for the mean-field critical behavior with respect to the source field in ferromagnets and ferroelectrics. Here reported hidden criticality of multiband superconductors can be experimentally observed by, e.g., imaging of the variations of the vortex core in a broader temperature range. Similar effects are expected for the superconducting multilayers.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 75
DOI: 10.1103/PhysRevLett.108.207002
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“Vortex-antivortex dynamics in mesoscopic symmetric and asymmetric superconducting loops with an applied ac current”. Zha G-Q, Peeters FM, Zhou S-P, Europhysics letters 108, 57001 (2014). http://doi.org/10.1209/0295-5075/108/57001
Abstract: In the framework of the time-dependent Ginzburg-Landau formalism, we study the dynamics of vortex-antivortex (V-Av) pairs in mesoscopic symmetric and asymmetric superconducting loops under an applied ac current. In contrast to the case of a constant biasing dc current, the process of the V-Av collision and annihilation is strongly affected by the time-periodic ac signal. As the direction of the applied ac current is reversed, the existed V-Av pair moves backward and then collides with a new created Av-V pair in a symmetric loop. In the presence of an appropriate external magnetic field, a novel sinusoidal-like oscillatory mode of the magnetization curve is observed, and the periodic dynamical process of the V-Av annihilation occurs in both branches of the sample. Moreover, for the asymmetric sample with an off-centered hole the creation point of the V-Av pair shifts away from the center of the sample, and the creation and annihilation dynamics of V-Av pairs turns out to be very different from the symmetric case. Copyright (C) EPLA, 2014
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 4
DOI: 10.1209/0295-5075/108/57001
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“Comparison of short-channel effects in monolayer MoS2 based junctionless and inversion-mode field-effect transistors”. Agarwal T, Sorée B, Radu I, Raghavan P, Fiori G, Iannaccone G, Thean A, Heyns M, Dehaene W, Applied physics letters 108, 023506 (2016). http://doi.org/10.1063/1.4939933
Abstract: Conventional junctionless (JL) multi/gate (MuG) field-effect transistors (FETs) require extremely scaled channels to deliver high on-state current with low short-channel effect related leakage. In this letter, using ultra-thin 2D materials (e.g., monolayer MoS2), we present comparison of short-channel effects in JL, and inversion-mode (IM) FETs. We show that JL FETs exhibit better sub-threshold slope (S.S.) and drain-induced-barrier-lowering (DIBL) in comparison to IM FETs due to reduced peak electric field at the junctions. But, threshold voltage (VT) roll-off with channel length downscaling is found to be significantly higher in JL FETs than IM FETs, due to higher source/drain controlled charges (dE/dx) in the channel. Further, we show that although VT roll-off in JL FETs improves by increasing the gate control, i.e., by scaling the oxide, or channel thickness, the sensitivity of threshold voltage on structural parameters is found out to be high. (C) 2016 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 13
DOI: 10.1063/1.4939933
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“Decoupled DFT-1/2 method for defect excitation energies”. Claes J, Partoens B, Lamoen D, Physical Review B 108, 125306 (2023). http://doi.org/10.1103/PhysRevB.108.125306
Abstract: The DFT-1/2 method is a band-gap correction with GW precision at a density functional theory (DFT) computational cost. The method was also extended to correct the gap between defect levels, allowing for the calculation of optical transitions. However, this method fails when the atomic character of the occupied and unoccupied defect levels is similar as we illustrate by two examples, the tetrahedral hydrogen interstitial and the negatively charged vacancy in diamond. We solve this problem by decoupling the effect of the occupied and unoccupied defect levels and call this the decoupled DFT-1/2 method for defects.
Keywords: A1 Journal Article; Condensed Matter Theory (CMT) ;
Impact Factor: 3.7
DOI: 10.1103/PhysRevB.108.125306
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“Phonon-mediated superconductivity in ternary silicides X₄, CoSi (X = Nb, Ta)”. Bekaert J, Physical review B 108, 134504 (2023). http://doi.org/10.1103/PHYSREVB.108.134504
Abstract: The superconducting properties of two recently synthesized ternary silicides with unit formula X<sub>4</sub>CoSi (X = Nb, Ta) are investigated through ab initio calculations combined with Eliashberg theory. Interestingly, their crystal structure comprises interlocking honeycomb networks of Nb/Ta atoms. Nb<sub>4</sub>CoSi is found to harbor better conditions for phonon-mediated superconductivity, as it possesses a higher density of states at the Fermi level, fostering stronger electron-phonon coupling. The superconducting critical temperatures (T<sub>c</sub>) follow the same trend, with Nb<sub>4</sub>CoSi having a twice higher value than Ta<sub>4</sub>CoSi. Furthermore, the calculated T<sub>c</sub> values (5.9 K vs 3.1 K) agree excellently with the experimentally obtained ones, establishing superconductivity in this new materials class as mediated by the electron-phonon coupling. Furthermore, my calculations show that the superconducting properties of these compounds do not simply correlate with the parameters of their honeycomb networks, contrary to proposals raised in the literature. Rather, their complete fermiology and phonon spectrum should be taken into account in order to explain their respective superconducting properties.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.108.134504
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“Silicon and germanium adamantane and diamantane monolayers as two-dimensional anisotropic direct-gap semiconductors”. Santos-Castro G, Pandey T, Bruno CHV, Santos Caetano EW, Milošević, MV, Chaves A, Freire VN, Physical review B 108, 035302 (2023). http://doi.org/10.1103/PHYSREVB.108.035302
Abstract: Structural and electronic properties of silicon and germanium monolayers with two different diamondoid crystal structures are detailed ab initio. Our results show that, despite Si and Ge being well-known indirect gap semiconductors in their bulk form, their adamantane and diamantane monolayers can exhibit optically active direct gap in the visible frequency range, with highly anisotropic effective masses, depending on the monolayer crystal structure. Moreover, we reveal that gaps in these materials are highly tunable with applied strain. These stable monolayer forms of Si and Ge are therefore expected to help bridging the gap between the fast growing area of opto-electronics in two-dimensional materials and the established silicon-based technologies.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
DOI: 10.1103/PHYSREVB.108.035302
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“Tuning of exciton type by environmental screening”. Lima ILC, Milošević, MV, Peeters FM, Chaves A, Physical review B 108, 115303 (2023). http://doi.org/10.1103/PHYSREVB.108.115303
Abstract: We theoretically investigate the binding energy and electron-hole (e-h) overlap of excitonic states confined at the interface between two-dimensional materials with type-II band alignment, i.e., with lowest conduction and highest valence band edges placed in different materials, arranged in a side-by-side planar heterostructure. We propose a variational procedure within the effective mass approximation to calculate the exciton ground state and apply our model to a monolayer MoS2/WS2 heterostructure. The role of nonabrupt interfaces between the materials is accounted for in our model by assuming a WxMo1-xS2 alloy around the interfacial region. Our results demonstrate that (i) interface-bound excitons are energetically favorable only for small interface thickness and/or for systems under high dielectric screening by the materials surrounding the monolayer, and that (ii) the interface exciton binding energy and its e-h overlap are controllable by the interface width and dielectric environment.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PHYSREVB.108.115303
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“Anharmonic effects on thermodynamic properties of a graphene monolayer”. da Silva ALC, Candido L, Teixeira Rabelo JN, Hai G-Q, Peeters FM, Europhysics letters 107, 56004 (2014). http://doi.org/10.1209/0295-5075/107/56004
Abstract: We extend the unsymmetrized self-consistent-field method (USF) for anharmonic crystals to layered non-Bravais crystals to investigate structural, dynamical and thermodynamic properties of a free-standing graphene monolayer. In this theory, the main anharmonicity of the crystal lattice has been included and the quantum corrections are taken into account in an h-expansion for the one-particle density matrix. The obtained result for the thermal expansion coefficient (TEC) of graphene shows a strong temperature dependence and agrees with experimental results by Bao et al. (Nat. Nanotechnol., 4 (2009) 562). The obtained value of TEC at room temperature (300 K) is -6.4 x 10(- 6) K- 1 and it becomes positive for T > T-alpha = 358K. We find that quantum effects are significant for T < 1000 K. The interatomic distance, effective amplitudes of the graphene lattice vibrations, adiabatic and isothermal bulk moduli, isobaric and isochoric heat capacities are also calculated and their temperature dependences are determined. Copyright (C) EPLA, 2014
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 1.957
Times cited: 23
DOI: 10.1209/0295-5075/107/56004
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“Classical nature of quantum dots in a magnetic field”. Anisimovas E, Matulis A, Peeters FM, Acta physica Polonica: A: general physics, solid state physics, applied physics 107, 188 (2005)
Abstract: A quasiclassical theory of few-electron quantum dots in a strong magnetic field is developed. The ground state energy and the corresponding many-electron wave function are obtained and used to derive a universal relation of critical magnetic fields and calculate the currents and the density-current correlation function.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 0.469
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“Formation of multiple-flux-quantum vortices in mesoscopic superconductors from simulations of calorimetric, magnetic, and transport properties”. Xu B, Milošević, MV, Lin S-H, Peeters FM, Jankó, B, Physical review letters 107, 057002 (2011). http://doi.org/10.1103/PhysRevLett.107.057002
Abstract: Because of strong flux confinement in mesoscopic superconductors, a giant vortex may appear in the ground state of the system in an applied magnetic field. This multiquanta vortex can then split into individual vortices (and vice versa) as a function of, e.g., applied current, magnetic field, or temperature. Here we show that such transitions can be identified by calorimetry, as the formation or splitting of a giant vortex results in a clear jump in measured heat capacity versus external drive. We attribute this phenomenon to an abrupt change in the density of states of the quasiparticle excitations in the vortex core(s), and further link it to a sharp change of the magnetic susceptibility at the transitionproving that the formation of a giant vortex can also be detected by magnetometry.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 26
DOI: 10.1103/PhysRevLett.107.057002
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“Magnetoresistance in a hybrid ferromagnetic/semiconductor device”. Papp G, Peeters FM, Journal of applied physics 107, 063718 (2010). http://doi.org/10.1063/1.3359652
Abstract: Ballistic transport of a two-dimensional electron gas (2DEG) in a rectangle shaped wire, subjected to a local nonhomogeneous magnetic field that results from an in-plane magnetized ferromagnetic (FM) strip deposited above the 2DEG, is investigated theoretically. We found a positive magnetoresistance (MR), which exhibits hysteresis behavior with respect to the direction of the magnetic field sweep, in agreement with a recent experiment. This positive MR can be tuned by applying a gate voltage to the FM strip.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 10
DOI: 10.1063/1.3359652
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“Nanotube field of C60 and C70 molecules in carbon nanotubes”. Verberck B, Michel KH, International journal of quantum chemistry 107, 2294 (2007). http://doi.org/10.1002/qua.21309
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.92
Times cited: 6
DOI: 10.1002/qua.21309
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“Rectification by an imprinted phase in a Josephson junction”. Berdiyorov GR, Milošević, MV, Covaci L, Peeters FM, Physical review letters 107, 177008 (2011). http://doi.org/10.1103/PhysRevLett.107.177008
Abstract: A Josephson phase shift can be induced in a Josephson junction by a strategically nearby pinned Abrikosov vortex (AV). For an asymmetric distribution of an imprinted phase along the junction (controlled by the position of the AV) such a simple system is capable of rectification of ac current in a broad and tunable frequency range. The resulting rectified voltage is a consequence of the directed motion of a Josephson antivortex which forms a pair with the AV when at local equilibrium. The proposed realization of the ratchet potential by an imprinted phase is more efficient than the asymmetric geometry of the junction itself, is easily realizable experimentally, and provides rectification even in the absence of an applied magnetic field.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 8.462
Times cited: 28
DOI: 10.1103/PhysRevLett.107.177008
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“Towards CMOS-compatible single-walled carbon nanotube resonators”. Pathangi H, Cherman V, Khaled A, Sorée B, Groeseneken G, Witvrouw A, Microelectronic engineering 107, 219 (2013). http://doi.org/10.1016/j.mee.2012.06.007
Abstract: We report a totally CMOS-compatible fabrication technique to assemble horizontally suspended single-walled carbon nanotube (SWCNT) resonators. Individual SWCNTs are assembled in parallel at multiple sites by a technique called dielectrophoresis. The mechanical resonance frequencies of the suspended SWCNTs are in the range of 2035 MHz as determined from the piezoresistive response of the resonators during electrostatic actuation. The resistance of the suspended SWCNT either remains unchanged or increases or decreases significantly as a function of the actuation frequency. This can be explained by the effect the nanotube chirality has on the piezoresistive gauge factor.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 1.806
Times cited: 6
DOI: 10.1016/j.mee.2012.06.007
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“Zener tunneling in semiconductors under nonuniform electric fields”. Vandenberghe W, Sorée B, Magnus W, Groeseneken G, Journal of applied physics 107, 054520 (2010). http://doi.org/10.1063/1.3311550
Abstract: Recently, a renewed interest in Zener tunneling has arisen because of its increasing impact on semiconductor device performance at nanometer dimensions. In this paper we evaluate the tunnel probability under the action of a nonuniform electric field using a two-band model and arrive at significant deviations from the commonly used Kanes model, valid for weak uniform fields only. A threshold on the junction bias where Kanes model for Zener tunneling breaks down is determined. Comparison with Kanes model particularly shows that our calculation yields a higher tunnel probability for intermediate electric fields and a lower tunnel probability for high electric fields. When performing a current calculation comparing to the WKB approximation for the case of an abrupt p-n junction significant differences concerning the shape of the I-V curve are demonstrated.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 22
DOI: 10.1063/1.3311550
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“Collapse of the low temperature insulating state in Cr-doped V2O3 thin films”. Homm P, Dillemans L, Menghini M, Van Bilzen B, Bakalov P, Su CY, Lieten R, Houssa M, Nasr Esfahani D, Covaci L, Peeters FM, Seo JW, Locquet JP;, Applied physics letters 107, 111904 (2015). http://doi.org/10.1063/1.4931372
Abstract: We have grown epitaxial Cr-doped V2O3 thin films with Cr concentrations between 0% and 20% on (0001)-Al2O3 by oxygen-assisted molecular beam epitaxy. For the highly doped samples (>3%), a regular and monotonous increase of the resistance with decreasing temperature is measured. Strikingly, in the low doping samples (between 1% and 3%), a collapse of the insulating state is observed with a reduction of the low temperature resistivity by up to 5 orders of magnitude. A vacuum annealing at high temperature of the films recovers the low temperature insulating state for doping levels below 3% and increases the room temperature resistivity towards the values of Cr-doped V2O3 single crystals. It is well-know that oxygen excess stabilizes a metallic state in V2O3 single crystals. Hence, we propose that Cr doping promotes oxygen excess in our films during deposition, leading to the collapse of the low temperature insulating state at low Cr concentrations. These results suggest that slightly Cr-doped V2O3 films can be interesting candidates for field effect devices. (C) 2015 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.411
Times cited: 14
DOI: 10.1063/1.4931372
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