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“All-strain based valley filter in graphene nanoribbons using snake states”. Cavalcante LS, Chaves A, da Costa DR, Farias GA, Peeters FM, Physical review B 94, 075432 (2016). http://doi.org/10.1103/PHYSREVB.94.075432
Abstract: A pseudomagnetic field kink can be realized along a graphene nanoribbon using strain engineering. Electron transport along this kink is governed by snake states that are characterized by a single propagation direction. Those pseudomagnetic fields point towards opposite directions in the K and K' valleys, leading to valley polarized snake states. In a graphene nanoribbon with armchair edges this effect results in a valley filter that is based only on strain engineering. We discuss how to maximize this valley filtering by adjusting the parameters that define the stress distribution along the graphene ribbon.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 29
DOI: 10.1103/PHYSREVB.94.075432
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“Broken one-particle symmetry in few-electron coupled quantum dots”. Chwiej T, Bednarek S, Adamowski J, Peeters FM, Physical review : B : condensed matter and materials physics 73, 075422 (2006). http://doi.org/10.1103/PhysRevB.73.075422
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 4
DOI: 10.1103/PhysRevB.73.075422
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“Influence of electron-electron interaction on the cyclotron resonance spectrum of magnetic quantum dots containing few electrons”. Nga TTN, Peeters FM, Physical review : B : condensed matter and materials physics 83, 075419 (2011). http://doi.org/10.1103/PhysRevB.83.075419
Abstract: The configuration interaction method is used to obtain the magneto-optical absorption spectrum of a few-electron (Ne=1,2,,5) quantum dot containing a single magnetic ion. We find that the IR spectrum (the position, the number, and the oscillator strength of the cyclotron resonance peaks) depends on the strength of the Coulomb interaction, the number of electrons, and the position of the magnetic ion. We find that the Kohn theorem is no longer valid as a consequence of the electron-spin-magnetic-ion-spin-exchange interaction.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.83.075419
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“Ab initio and semiempirical modeling of excitons and trions in monolayer TiS3”. Torun E, Sahin H, Chaves A, Wirtz L, Peeters FM, Physical review B 98, 075419 (2018). http://doi.org/10.1103/PHYSREVB.98.075419
Abstract: We explore the electronic and the optical properties of monolayer TiS3, which shows in-plane anisotropy and is composed of a chain-like structure along one of the lattice directions. Together with its robust direct band gap, which changes very slightly with stacking order and with the thickness of the sample, the anisotropic physical properties of TiS3 make the material very attractive for various device applications. In this study, we present a detailed investigation on the effect of the crystal anisotropy on the excitons and the trions of the TiS3 monolayer. We use many-body perturbation theory to calculate the absorption spectrum of anisotropic TiS3 monolayer by solving the Bethe-Salpeter equation. In parallel, we implement and use a Wannier-Mott model for the excitons that takes into account the anisotropic effective masses and Coulomb screening, which are obtained from ab initio calculations. This model is then extended for the investigation of trion states of monolayer TiS3. Our calculations indicate that the absorption spectrum of monolayer TiS3 drastically depends on the polarization of the incoming light, which excites different excitons with distinct binding energies. In addition, the binding energies of positively and the negatively charged trions are observed to be distinct and they exhibit an anisotropic probability density distribution.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 10
DOI: 10.1103/PHYSREVB.98.075419
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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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“Quantum transport in defective phosphorene nanoribbons : effects of atomic vacancies”. Li LL, Peeters FM, Physical review B 97, 075414 (2018). http://doi.org/10.1103/PHYSREVB.97.075414
Abstract: Defects are almost inevitably present in realistic materials and defective materials are expected to exhibit very different properties than their nondefective (perfect) counterparts. Here, using a combination of the tight-binding approach and the scattering matrix formalism, we investigate the electronic transport properties of defective phosphorene nanoribbons (PNRs) containing atomic vacancies. We find that for both armchair PNRs (APNRs) and zigzag PNRs (ZPNRs), single vacancies can create quasilocalized states, which can affect their conductance. With increasing vacancy concentration, three different transport regimes are identified: ballistic, diffusive, and Anderson localized ones. In particular, ZPNRs that are known to be metallic due to the presence of edge states become semiconducting: edge conductance vanishes and transport gap appears due to Anderson localization. Moreover, we find that for a fixed vacancy concentration, both APNRs and ZPNRs of narrower width and/or longer length are more sensitive to vacancy disorder than their wider and/or shorter counterparts, and that for the same ribbon length and width, ZPNRs are more sensitive to vacancy disorder than APNRs.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 30
DOI: 10.1103/PHYSREVB.97.075414
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“Interfacial characteristics, Schottky contact, and optical performance of a graphene/Ga2SSe van der Waals heterostructure: Strain engineering and electric field tunability”. Nguyen HTT, Obeid MM, Bafekry A, Idrees M, Vu TV, Phuc H V, Hieu NN, Le Hoa T, Amin B, Nguyen C V, Physical Review B 102, 075414 (2020). http://doi.org/10.1103/PHYSREVB.102.075414
Abstract: Two-dimensional graphene-based van der Waals heterostructures have received considerable interest because of their intriguing characteristics compared with the constituent single-layer two-dimensional materials. Here, we investigate the interfacial characteristics, Schottky contact, and optical performance of graphene/Ga2SSe van der Waals (vdW) heterostructure using first-principles calculations. The effects of stacking patterns, electric gating, and interlayer coupling on the interfacial properties of graphene/Ga2SSe heterostructures are also examined. Our results demonstrate that the Dirac cone of graphene is well preserved at the F point in all stacking patterns due to the weak vdW interactions, which keep the heterostructures feasible such that they can be obtained in further experiments. Moreover, depending on the stacking patterns, a small band gap of about 13-17 meV opens in graphene and has a high carrier mobility, indicating that the graphene/Ga2SSe heterostructures are potential candidates for future high-speed nanoelectronic applications. In the ground state, the graphene/Ga2SSe heterostructures form an n-type Schottky contact. The transformation from an n-type to a p-type Schottky contact or to an Ohmic contact can be forced by electric gating or by varying the interlayer coupling. Our findings could provide physical guidance for designing controllable Schottky nanodevices with high electronic and optical performances.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 12
DOI: 10.1103/PHYSREVB.102.075414
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“TiS3 nanoribbons : width-independent band gap and strain-tunable electronic properties”. Kang J, Sahin H, Ozaydin HD, Senger RT, Peeters FM, Physical review : B : condensed matter and materials physics 92, 075413 (2015). http://doi.org/10.1103/PhysRevB.92.075413
Abstract: The electronic properties, carrier mobility, and strain response of TiS3 nanoribbons (TiS3 NRs) are investigated by first-principles calculations. We found that the electronic properties of TiS3 NRs strongly depend on the edge type (a or b). All a-TiS3 NRs are metallic with a magnetic ground state, while b-TiS3 NRs are direct band gap semiconductors. Interestingly, the size of the band gap and the band edge position are almost independent of the ribbon width. This feature promises a constant band gap in a b-TiS3 NR with rough edges, where the ribbon width differs in different regions. The maximum carrier mobility of b-TiS3 NRs is calculated by using the deformation potential theory combined with the effective mass approximation and is found to be of the order 10(3) cm(2) V-1 s(-1). The hole mobility of the b-TiS3 NRs is one order of magnitude lower, but it is enhanced compared to the monolayer case due to the reduction in hole effective mass. The band gap and the band edge position of b-TiS3 NRs are quite sensitive to applied strain. In addition we investigate the termination of ribbon edges by hydrogen atoms. Upon edge passivation, the metallic and magnetic features of a-TiS3 NRs remain unchanged, while the band gap of b-TiS3 NRs is increased significantly. The robust metallic and ferromagnetic nature of a-TiS3 NRs is an essential feature for spintronic device applications. The direct, width-independent, and strain-tunable band gap, as well as the high carrier mobility, of b-TiS3 NRs is of potential importance in many fields of nanoelectronics, such as field-effect devices, optoelectronic applications, and strain sensors.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 55
DOI: 10.1103/PhysRevB.92.075413
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“Circular quantum dots in twisted bilayer graphene”. Mirzakhani M, Peeters FM, Zarenia M, Physical Review B 101, 075413 (2020). http://doi.org/10.1103/PHYSREVB.101.075413
Abstract: Within a tight-binding approach, we investigate the effect of twisting angle on the energy levels of circular bilayer graphene (BLG) quantum dots (QDs) in both the absence and presence of a perpendicular magnetic field. The QDs are defined by an infinite-mass potential, so that the specific edge effects are not present. In the absence of magnetic field (or when the magnetic length is larger than the moire length), we show that the low-energy states in twisted BLG QDs are completely affected by the formation of moire patterns, with a strong localization at AA-stacked regions. When magnetic field increases, the energy gap of an untwisted BLG QD closes with the edge states, localized at the boundaries between the AA- and AB-stacked spots in a twisted BLG QD. Our observation of the spatial localization of the electrons in twisted BLG QDs can be experimentally probed by low-bias scanning tunneling microscopy measurements.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 19
DOI: 10.1103/PHYSREVB.101.075413
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“Strong anisotropic optical conductivity in two-dimensional puckered structures : the role of the Rashba effect”. Saberi-Pouya S, Vazifehshenas T, Salavati-Fard T, Farmanbar M, Peeters FM, Physical review B 96, 075411 (2017). http://doi.org/10.1103/PHYSREVB.96.075411
Abstract: within the Kubo formalism. We show that the anisotropic Rashba effect caused by an external field significantly changes the magnitude of the spin splitting. Furthermore, we obtain an analytical expression for the longitudinal optical conductivity associated with interband transitions as a function of the frequency for arbitrary polarization angle. We find that the diagonal components of the optical conductivity tensor are direction dependent and the optical absorption spectrum exhibits a strongly anisotropic absorption window. The height and width of this absorption window are very sensitive to the anisotropy of the system. While the height of absorption peak increases with increasing effective mass anisotropy ratio, the peak intensity is larger when the light polarization is along the armchair direction. Moreover, the absorption peak width becomes broader as the density-of-states mass or Rashba interaction is enhanced. These features in the optical absorption spectrum can be used to determine parameters relevant for spintronics.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 16
DOI: 10.1103/PHYSREVB.96.075411
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“In situ study of the \alpha-Sn to \beta-Sn phase transition in low-dimensional systems : phonon behavior and thermodynamic properties”. Houben K, Jochum JK, Lozano DP, Bisht M, Menendez E, Merkel DG, Ruffer R, Chumakov A I, Roelants S, Partoens B, Milošević, MV, Peeters FM, Couet S, Vantomme A, Temst K, Van Bael MJ, Physical review B 100, 075408 (2019). http://doi.org/10.1103/PHYSREVB.100.075408
Abstract: The densities of phonon states of thin Sn films on InSb substrates are determined during different stages of the alpha-Sn to beta-Sn phase transition using nuclear inelastic x-ray scattering. The vibrational entropy and internal energy per atom as a function of temperature are obtained by numerical integration of the phonon density of states. The free energy as a function of temperature for the nanoscale samples is compared to the free energy obtained from ab initio calculations of bulk tin in the alpha-Sn and beta-Sn phase. In thin films this phase transition is governed by the interplay between the vibrational behavior of the film (the phase transition is driven by the vibrational entropy) and the stabilizing influence of the substrate (which depends on the film thickness). This brings a deeper understanding of the role of lattice vibrations in the phase transition of nanoscale Sn.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PHYSREVB.100.075408
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“Trions in cylindrical nanowires with a dielectric mismatch”. Slachmuylders AF, Partoens B, Magnus W, Peeters FM, Physical review : B : condensed matter and materials physics 76, 075405 (2007). http://doi.org/10.1103/PhysRevB.76.075405
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 12
DOI: 10.1103/PhysRevB.76.075405
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“From graphene to graphite: electronic structure around the K point”. Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 74, 075404 (2006). http://doi.org/10.1103/PhysRevB.74.075404
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 738
DOI: 10.1103/PhysRevB.74.075404
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“Landau-level broadening due to electron-impurity interaction in graphene in strong magnetic fields”. Yang CH, Peeters FM, Xu W, Physical review : B : condensed matter and materials physics 82, 075401:1 (2010). http://doi.org/10.1103/PhysRevB.82.075401
Abstract: The effect of electron-impurity and electron-electron interactions on the energy spectrum of electrons moving in graphene is investigated in the presence of a high magnetic field. We find that the width of the broadened Landau levels exhibits an approximate 1/B dependence near half filling for charged impurity scattering. The Landau-level width, the density of states, and the Fermi energy exhibit an oscillatory behavior as a function of magnetic field. Comparison with experiment shows that scattering with charged impurities cannot be the main scattering mechanism that determines the width of the Landau levels.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PhysRevB.82.075401
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“Multiband flattening and linear Dirac band structure in graphene with impurities”. Ahmadkhani S, Alihosseini M, Ghasemi S, Ahmadabadi I, Hassani N, Peeters FM, Neek-Amal M, Physical review B 107, 075401 (2023). http://doi.org/10.1103/PHYSREVB.107.075401
Abstract: Flat bands in the energy spectrum have attracted a lot of attention in recent years because of their unique properties and promising applications. Special arrangement of impurities on monolayer graphene are proposed to generate multiflat bands in the electronic band structure. In addition to the single midgap states in the spectrum of graphene with low hydrogen density, we found closely spaced bands around the Fermi level with increasing impurity density, which are similar to discrete lines in the spectrum of quantum dots, as well as the unusual Landau-level energy spectrum of graphene in the presence of a strong magnetic field. The presence of flat bands crucially depends on whether or not there are odd or even electrons of H(F) atoms bound to graphene. Interestingly, we found that a fully hydrogenated (fluoridated) of a hexagon of graphene sheet with six hydrogen (fluorine) atoms sitting on top and bottom in consecutive order exhibits Dirac cones in the electronic band structure with a 20% smaller Fermi velocity as compared to the pristine graphene. Functionalizing graphene introduces various C-C bond lengths resulting in nonuniform strains. Such a nonuniform strain may induce a giant pseudomagnetic field in the system, resulting in quantum Hall effect.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.7
Times cited: 1
DOI: 10.1103/PHYSREVB.107.075401
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“Magnetoconductance through a chain of rings with or without periodically modulated spin-orbit interaction strength and magnetic field”. Molnár B, Vasilopoulos P, Peeters FM, Physical review : B : condensed matter and materials physics 72, 075330 (2005). http://doi.org/10.1103/PhysRevB.72.075330
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 52
DOI: 10.1103/PhysRevB.72.075330
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“Optical properties of free-standing GaAs semiconductor nanowires and their dependence on the growth direction”. Redli<<0144>>ski P, Peeters FM, Physical review : B : condensed matter and materials physics 77, 075329 (2008). http://doi.org/10.1103/PhysRevB.77.075329
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 21
DOI: 10.1103/PhysRevB.77.075329
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“Dependence of the vortex structure in quantum dots on the range of the inter-electron interaction”. Stopa T, Szafran B, Tavernier MB, Peeters FM, Physical review : B : condensed matter and materials physics 73, 075315 (2006). http://doi.org/10.1103/PhysRevB.73.075315
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 7
DOI: 10.1103/PhysRevB.73.075315
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“Single and vertically coupled type-II quantum dots in a perpendicular magnetic field: exciton ground-state properties”. Janssens KL, Partoens B, Peeters FM, Physical review : B : condensed matter and materials physics 66, 075314 (2002). http://doi.org/10.1103/PhysRevB.66.075314
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 38
DOI: 10.1103/PhysRevB.66.075314
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“Effect of a perpendicular magnetic field on the shallow donor states near a semiconductor-metal interface”. Li B, Djotyan AP, Hao YL, Avetisyan AA, Peeters FM, Physical review : B : condensed matter and materials physics 87, 075313 (2013). http://doi.org/10.1103/PhysRevB.87.075313
Abstract: We investigate the influence of an external perpendicular magnetic field on the lowest-energy states of an electron bound to a donor which is located near a semiconductor-metal interface. The problem is treated within the effective mass approach and the lowest-energy states are obtained through (1) the “numerically exact” finite element method, and (2) a variational approach using a trial wave function where all image charges that emerge due to the presence of the metallic gate are taken into account. The trial wave functions are constructed such that they reduce to an exponential behavior for sufficiently small magnetic fields and become Gaussian for intermediate and large magnetic fields. The average electron-donor distance can be controlled by the external magnetic field. We find that the size of the 2p(z) state depends strongly on the magnetic field when the donor is close to the interface, showing a nonmonotonic behavior, in contrast with the ground and the other excited states. DOI: 10.1103/PhysRevB.87.075313
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 1
DOI: 10.1103/PhysRevB.87.075313
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“Dynamic response of artificial bipolar molecules”. Anisimovas E, Peeters FM, Physical review : B : condensed matter and materials physics 66, 075311 (2002). http://doi.org/10.1103/PhysRevB.66.075311
Abstract: We calculate the equilibrium properties and the dynamic response of two vertically coupled circular quantum dots populated by particles of different electrical charge sign, i.e., electrons and holes. The equilibrium density profiles are obtained and used to compute the frequencies and oscillator strengths of magnetoplasma excitations. We find a strong coupling between the modes derived from the center-of-mass modes of the individual dots which leads to an anticrossing with a pronounced oscillator strength transfer from the “acoustic” to the “optical” branch. Also, due to the breaking of the generalized Kohn theorem a number of other than center-of-mass modes are excited whose oscillator strengths, however, are rather weak.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 9
DOI: 10.1103/PhysRevB.66.075311
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“Competition between pure dephasing and photon losses in the dynamics of a dot-cavity system”. Vagov A, Glaessl M, Croitoru MD, Axt VM, Kuhn T, Physical review : B : condensed matter and materials physics 90, 075309 (2014). http://doi.org/10.1103/PhysRevB.90.075309
Abstract: We demonstrate that in quantum-dot cavity systems, the interplay between acoustic phonons and photon losses introduces novel features and characteristic dependencies in the system dynamics. In particular, the combined action of both dephasing mechanisms strongly affects the transition from the weak-to the strong-coupling regime as well as the shape of the spectral triplet that represents the quantum-dot occupation in Fourier space. The width of the central peak in the triplet is expected to decrease with rising temperature, while the widths and heights of the side peaks depend nonmonotonically on the dot-cavity coupling.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 11
DOI: 10.1103/PhysRevB.90.075309
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“Power-law dependence of the angular momentum transition fields in few-electron quantum dots”. Anisimovas E, Matulis A, Tavernier MB, Peeters FM, Physical review : B : condensed matter and materials physics 69, 075305 (2004). http://doi.org/10.1103/PhysRevB.69.075305
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 12
DOI: 10.1103/PhysRevB.69.075305
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“Vibrational properties of germanane and fluorinated germanene in the chair, boat, and zigzag-line configurations”. Rivera-Julio J, Gonzalez-Garcia A, Gonzalez-Hernandez R, Lopez-Perez W, Peeters FM, Hernandez-Nieves AD, Journal of physics : condensed matter 31, 075301 (2019). http://doi.org/10.1088/1361-648X/AAF45F
Abstract: The electronic and vibrational properties of germanane and fluorinated germanene are studied within density functional theory (DFT) and density functional perturbation theory frameworks. Different structural configurations of germanane and fluorinated germanene are investigated. The energy difference between the different configurations are consistently smaller than the energy of thermal fluctuations for all the analyzed DFT functionals LDA, GGA, and hybrid functionals, which implies that, in principle, it is possible to find these different configurations in different regions of the sample as minority phases or local defects. We calculate the Raman and infrared spectra for these configurations by using ab initio calculations and compare it with available experimental spectra for germanane. Our results show the presence of minority phases compatible with the configurations analyzed in this work. As these low energy configurations are metastable the present work shows that the synthesis of these energy competing phases is feasible by selectively changing the synthesis conditions, which is an opportunity to expand in this way the availability of new two-dimensional compounds.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.649
Times cited: 9
DOI: 10.1088/1361-648X/AAF45F
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“Crystal fields, disorder, and antiferromagnetic short-range order in Yb0.24Sn0.76Ru”. Klimczuk T, Wang CH, Lawrence JM, Xu Q, Durakiewicz T, Ronning F, Llobet A, Trouw F, Kurita N, Tokiwa Y, Lee Ho, Booth CH, Gardner JS, Bauer ED, Joyce JJ, Zandbergen HW, Movshovich R, Cava RJ, Thompson JD;, Physical review : B : condensed matter and materials physics 84, 075152 (2011). http://doi.org/10.1103/PhysRevB.84.075152
Abstract: We report extensive measurements on a new compound (Yb0.24Sn0.76)Ru that crystallizes in the cubic CsCl structure. Valence-band photoemission (PES) and L3 x-ray absorption show no divalent component in the 4f configuration of Yb. Inelastic neutron scattering (INS) indicates that the eight-fold degenerate J-multiplet of Yb3+ is split by the crystalline electric field (CEF) into a Γ7-doublet ground state and a Γ8 quartet at an excitation energy 20 meV. The magnetic susceptibility can be fit very well by this CEF scheme under the assumption that a Γ6-excited state resides at 32 meV; however, the Γ8/Γ6 transition expected at 12 meV was not observed in the INS. The resistivity follows a Bloch-Grüneisen law shunted by a parallel resistor, as is typical of systems subject to phonon scattering with no apparent magnetic scattering. All of these properties can be understood as representing simple local moment behavior of the trivalent Yb ion. At 1 K there is a peak in specific heat that is too broad to represent a magnetic-phase transition, consistent with absence of magnetic reflections in neutron diffraction. On the other hand this peak also is too narrow to represent the Kondo effect in the Γ7-doublet ground state. On the basis of the field dependence of the specific heat, we argue that antiferromagnetic (AF) short-range order (SRO) (possibly coexisting with Kondo physics) occurs at low temperatures. The long-range magnetic order is suppressed because the Yb site occupancy is below the percolation threshold for this disordered compound.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.836
Times cited: 8
DOI: 10.1103/PhysRevB.84.075152
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“Optical properties of GaS-Ca(OH)2 bilayer heterostructure”. Torun E, Sahin H, Peeters FM, Physical review B 93, 075111 (2016). http://doi.org/10.1103/PhysRevB.93.075111
Abstract: Finding novel atomically thin heterostructures and understanding their characteristic properties are critical for developing better nanoscale optoelectronic devices. In this study, we investigate the electronic and optical properties of a GaS-Ca(OH)(2) heterostructure using first-principle calculations. The band gap of the GaS-Ca(OH)(2) heterostructure is significantly reduced when compared to those of the isolated constituent layers. Our calculations showthat the GaS-Ca(OH)(2) heterostructure is a type-II heterojunction which can be used to separate photoinduced charge carriers where electrons are localized in GaS and holes in the Ca(OH)(2) layer. This leads to spatially indirect excitons which are important for solar energy and optoelectronic applications due to their long lifetime. By solving the Bethe-Salpeter equation on top of a single shot GW calculation (G(0)W(0)), the dielectric function and optical oscillator strength of the constituent monolayers and the heterostructure are obtained. The oscillator strength of the optical transition for the GaS monolayer is an order of magnitude larger than the Ca(OH)(2) monolayer. We also found that the calculated optical spectra of different stacking types of the heterostructure show dissimilarities, although their electronic structures are rather similar. This prediction can be used to determine the stacking type of ultrathin heterostructures.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.836
Times cited: 18
DOI: 10.1103/PhysRevB.93.075111
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“Anisotropic electronic, mechanical, and optical properties of monolayer WTe2”. Torun E, Sahin H, Cahangirov S, Rubio A, Peeters FM, Journal of applied physics 119, 074307 (2016). http://doi.org/10.1063/1.4942162
Abstract: Using first-principles calculations, we investigate the electronic, mechanical, and optical properties of monolayer WTe2. Atomic structure and ground state properties of monolayer WTe2 (T-d phase) are anisotropic which are in contrast to similar monolayer crystals of transition metal dichalcogenides, such as MoS2, WS2, MoSe2, WSe2, and MoTe2, which crystallize in the H-phase. We find that the Poisson ratio and the in-plane stiffness is direction dependent due to the symmetry breaking induced by the dimerization of the W atoms along one of the lattice directions of the compound. Since the semimetallic behavior of the T-d phase originates from this W-W interaction (along the a crystallographic direction), tensile strain along the dimer direction leads to a semimetal to semiconductor transition after 1% strain. By solving the Bethe-Salpeter equation on top of single shot G(0)W(0) calculations, we predict that the absorption spectrum of T-d-WTe2 monolayer is strongly direction dependent and tunable by tensile strain. (C) 2016 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 62
DOI: 10.1063/1.4942162
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“Electronic properties of graphene nano-flakes : energy gap, permanent dipole, termination effect, and Raman spectroscopy”. Singh SK, Neek-Amal M, Peeters FM, The journal of chemical physics 140, 074304 (2014). http://doi.org/10.1063/1.4865414
Abstract: The electronic properties of graphene nano-flakes (GNFs) with different edge passivation are investigated by using density functional theory. Passivation with F and H atoms is considered: C-Nc X-Nx (X = F or H). We studied GNFs with 10 < N-c < 56 and limit ourselves to the lowest energy configurations. We found that: (i) the energy difference Delta between the highest occupied molecular orbital and the lowest unoccupied molecular orbital decreases with N-c, (ii) topological defects (pentagon and heptagon) break the symmetry of the GNFs and enhance the electric polarization, (iii) the mutual interaction of bilayer GNFs can be understood by dipole-dipole interaction which were found sensitive to the relative orientation of the GNFs, (iv) the permanent dipoles depend on the edge terminated atom, while the energy gap is independent of it, and (v) the presence of heptagon and pentagon defects in the GNFs results in the largest difference between the energy of the spin-up and spin-down electrons which is larger for the H-passivated GNFs as compared to F-passivated GNFs. Our study shows clearly the effect of geometry, size, termination, and bilayer on the electronic properties of small GNFs. This study reveals important features of graphene nano-flakes which can be detected using Raman spectroscopy. (C) 2014 AIP Publishing LLC.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.965
Times cited: 30
DOI: 10.1063/1.4865414
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“Axion insulator states in a topological insulator proximitized to magnetic insulators : a tight-binding characterization”. Shafiei M, Fazileh F, Peeters FM, Milošević, MV, Physical review materials 6, 074205 (2022). http://doi.org/10.1103/PHYSREVMATERIALS.6.074205
Abstract: The recent discovery of axion states in materials such as antiferromagnetic topological insulators has boosted investigations of the magnetoelectric response in topological insulators and their promise towards realizing dissipationless topological electronics. In this paper, we develop a tight-binding methodology to explore the emergence of axion states in Bi2Se3 in proximity to magnetic insulators on the top and bottom surfaces. The topological protection of the surface states is lifted by a time-reversal-breaking perturbation due to the proximity of a magnetic insulator, and a gap is opened on the surfaces, giving rise to half-quantized Hall conductance and a zero Hall plateau-evidencing an axion insulator state. We developed a real-space tight-binding Hamiltonian for Bi2Se3 using first-principles data. Transport properties of the system were obtained within the Landauer-Buttiker formalism, and we discuss the creation of axion states through Hall conductance and a zero Hall plateau at the surfaces, as a function of proximitized magnetization and corresponding potentials at the surfaces, as well as the thickness of the topological insulator.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.4
Times cited: 4
DOI: 10.1103/PHYSREVMATERIALS.6.074205
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“Slippage dynamics of confined water in graphene oxide capillaries”. Kalashami HG, Neek-Amal M, Peeters FM, Physical review materials 2, 074004 (2018). http://doi.org/10.1103/PHYSREVMATERIALS.2.074004
Abstract: The permeation of water between neighboring graphene oxide (GO) flakes, i.e., 2D nanochannels, are investigated using a simple model for the GO membrane. We simulate the hydrophilic behavior of nanocapillaries and study the effect of surface charge on the dynamical properties of water flow and the influence of Na+ and Cl- ions on water permeation. Our approach is based on extensive equilibrium molecular dynamics simulations to obtain a better understanding of water permeation through charged nanochannels in the presence of ions. We found significant change in the slippage dynamics of confined water such as a profound increase in viscosity/slip length with increasing charges over the surface. The slip length decreases one order of magnitude (i.e., 1/30) with increasing density of surface charge, while it increases by a factor of 2 with ion concentration. We found that commensurability induced by nanoconfinement plays an important role on the intrinsic dynamical properties of water.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Times cited: 1
DOI: 10.1103/PHYSREVMATERIALS.2.074004
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