journal

# Journal of Physics. Condensed Matter: An Institute of Physics Journal

journal
#1
Ning Xu, Haiyang Zhang, Xiuqiang Wu, Chen Qiao, Jian-Wen Ding
Based on the tight-binding model, charge and spin transport properties of hexagonal silicene rings are investigated within the nonequilibrium Green's function technique. The effects of external electric, magnetic and exchange fields are taken into account. The calculated results reveal that the hexagonal silicene nanorings act as a controllable spin filter. The near-perfect spin polarization can be achieved by adjusting electric, magnetic and exchange fields. The calculated results offer new possibilities for silicene ring based spin nanodevices...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#2
Benedikt Röska, So-Hyun Park, Yusuke Yoshimori, Kenta Kimura, Tsuyoshi Kimura
An anomalous increase in the real part of dielectric response is observed in Mn<sub>0.5</sub>Fe<sub>0.5</sub>AlPO<sub>4</sub>(OH)<sub>2</sub>H<sub>2</sub>O while cooling to ~70 K. This is addressed to field-induced proton dynamics in a short hydrogen bond of 2.480(3) Å. The absence of discontinuities in heat capacity curves above the Néel temperature (T<sub>N</sub> ≈ 7 K) excludes a paraelectric to antiferroelectric phase transition...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#3
Andrey Turlapov, Maxim Yu Kagan
Physics of many-body systems where particles are restricted to move in two spatial dimensions is challenging and even controversial: On one hand, neither long-range order nor Bose condensation may appear in infinite uniform 2D systems at finite temperature, on the other hand this does not prohibit superfluidity or superconductivity. Moreover, 2D superconductors, such as cuprates, are among the systems with highest critical temperatures. Ultracold atoms are a platform for studying 2D physics. Uniquely to other physical systems, quantum statistics may be completely changed in an ultracold gas: an atomic Fermi gas may be smoothly crossed over into a gas of Bose molecules (or dimers) by tuning interatomic interactions...
June 21, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#4
Simon A Hunt, Elizabeth Wann, David Dobson, Lidunka Vočadlo, Ian Wood
We have measured the thermal expansion of (Fe<sub>1-<i>y</i></sub>Ni<sub><i>y</i></sub>)Si for <i>y</i> = 0, 0.1 and 0.2, between 40 and 1273 K. Above ∽700 K the unit-cell volumes of the samples decrease approximately linearly with increasing Ni content. Below ∽200 K the unit-cell volume of FeSi falls to a value between that of (Fe<sub>0.9</sub>Ni<sub>0.1</sub>)Si and (Fe<sub>0.8</sub>Ni<sub>0.2</sub>)Si...
June 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#5
Karim Essafi, Ludovic D C Jaubert, Masafumi Udagawa
In breathing pyrochlores and kagomes, couplings between neighbouring tetrahedra and triangles are free to differ. Breathing lattices thus offer the possibility to explore a different facet of the rich physics of these systems. Here we consider nearest-neighbour classical Heisenberg interactions, both ferromagnetic and antiferromagnetic, and study how the anisotropy of breathing lattices modifies the mode spectrum of pyrochlore and kagome systems. The nature and degeneracy of the flat bands are shown to be preserved for any value of the anisotropy...
June 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#6
Tao Du, Yue-Xun Li, Yan Li, He-Lin Lu, Hui Zhang
The dimerized Kane-Mele model with/without the strong interaction is studied using analytical methods. The boundary of the topological phase transition of the model without strong interaction is obtained. Our results show that the occurrence of the transition only depends on dimerized parameter α . From the one-particle spectrum, we obtain the completed phase diagram including the quantum spin Hall (QSH) state and the topologically trivial insulator. Then, using different mean-field methods, we investigate the Mott transition and the magnetic transition of the strongly correlated dimerized Kane-Mele model...
June 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#7
S S Kubakaddi, Tutul Biswas, Tarun Kanti Ghosh
A theory of low-temperature phonon-drag magnetothermopower [Formula: see text] is presented in graphene in a quantizing magnetic field. [Formula: see text] is found to exhibit quantum oscillations as a function of magnetic field B and electron concentration n e . The amplitude of the oscillations is found to increase (decrease) with increasing B (n e ). The behavior of [Formula: see text] is also investigated as a function of temperature. A large value of [Formula: see text] (∼few hundreds of μV K(-1)) is predicted...
June 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#8
Ulrike Stockert, Ricardo Donizeth Dos Reis, M O Ajeesh, Sarah J Watzman, Marcus Schmidt, Chandra Shekhar, Joseph P Heremans, Claudia Felser, Michael Baenitz, Michael Nicklas
The Weyl semimetal NbP exhibits an extremely large magnetoresistance (MR) and an ultra-high mobility. The large MR originates from a combination of the nearly perfect compensation between electron- and hole-type charge carriers and the high mobility, which is relevant to the topological band structure. In this work we report on temperature- and field-dependent thermopower and thermal conductivity experiments on NbP. Additionally, we carried out complementary heat capacity, magnetization, and electrical resistivity measurements...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#9
Sebastian Bauer, Christian Alexander Bobisch
We analyse the electron transport in a 16 quintuple layer (QL) thick stepped Bi<sub>2</sub>Se<sub>3</sub> film grown on Si(111) by means of scanning tunnelling potentiometry (STP) and multi-point probe (MPP) measurements. Scanning tunnelling microscopy (STM) images reveal that the local structure of the Bi<sub>2</sub>Se<sub>3</sub> film is dominated by terrace steps and domain boundaries. From a microscopic study on the nm scale by STP, we find a mostly linear gradient of the voltage on the Bi<sub>2</sub>Se<sub>3</sub> terraces which is interrupted by voltage drops at the position of the domain boundaries...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#10
Bao-Tian Wang, Elena Roxana Margine
The recent discovery of topologically protected surface states in the noncentrosymmetric α-BiPd and the centrosymmetric β-Bi<sub>2</sub>Pd has renewed the interest in the Bi-Pd family of superconductors. We employ first-principles calculations to investigate the electronic structure and topological features of β-Bi<sub>2</sub>Pd, in bulk and in thin films of various thicknesses. We find that films of nine or more triple layers could harbor topological surface states with Dirac- and Rashba-like band dispersion...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#11
Marcin Abram, Michal Zegrodnik, Jozef Spalek
In the frst part of the paper, we study the stability of antiferromagnetic (AF), charge density wave (CDW), and superconducting (SC) states within the t-J-U-V model of strongly correlated electrons by using the statistically consistent Gutzwiller approximation (SGA). We concentrate on the role of the intersite Coulomb interaction term V in stabilizing the CDW phase. In particular, we show that the charge ordering appears only above a critical value of V in a limited hole-doping range $\delta$. The effect of the V term on SC and AF phases is that a strong interaction suppresses SC, whereas the AF order is not significantly influenced by its presence...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#12
Juan J Alonso, Bartolome Alles
Using tempered Monte Carlo simulations, we study the the spin-glass phase of dense packings of Ising dipoles pointing along random axes. We consider systems of dipoles (i) placed on the sites of a simple cubic lattice with lattice constant d, and (ii) placed at the center of random close packed spheres of diameter d that occupy a 64% of the volume. For both cases we find a spin-glass phase below a certain temperature T_sg . By analysing the data obtained for the overlap parameter, the associated correlation length, as well as the statistics of the overlap distributions of individual samples, we find a behavior consistent with quasi-long-range order in the spin-glass phase, similar to the one previously found in strongly diluted dipolar systems...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#13
Neus Domingo, Saeedeh Farokhipoor, Jose Santiso, Beatriz Noheda, Gustau Catalan
We measure the magnetotransport properties of individual 71º domain walls in multiferroic BiFeO3 by means of conductive - atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#14
Noeliarinala Felana Andriambelaza, Edwin Mapasha, Nithaya Chetty
Density functional theory (DFT) calculations have been performed to study the thermodynamic stability, structural and electronic properties of various chromium (Cr) line-ordered alloy configurations in a molybdenum disulfide (MoS<sub>2</sub>) hexagonal monolayer for band gap engineering. Only the molybdenum (Mo) sites were substituted at each concentration in this study. For comparison purpose, different Cr line-ordered alloy and random alloy configurations were studied and the most thermodynamically stable ones at each concentration were identified...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#15
Jorge Jose Kohanoff, Maeve McAllister, Gareth Tribello, Bin Gu
DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts from the interaction of radiation -- either photons or swift ions -- with the biological medium. Such interactions cause electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals...
June 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#16
Carlos Trallero-Giner, Johnni Xavier Padilha, Victor Lopez-Richard, Gilmar Marques, L Castelano
We report the energy spectrum and the eigenstates of conduction and uncoupled valence bands of a quantum well under the influence of a tilted magnetic field. In the framework of the envelope approximation, we implement two analytical approaches to obtain the nontrivial solutions of the tilted magnetic field: a) the Bubnov-Galerkin spectral method and b) the perturbation theory. We discuss the validity of each method for a broad range of magnetic field intensity and orientation as well as quantum well thickness...
June 14, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#17
Alexander Wagenpfahl
Modern solar cell technologies are coined by the effort to enhance power conversion efficiencies. Limiting influences are manifold. Undoubtedly, the loss of electrical charge carriers, the charge carrier recombination, is one of the most prominent process which may lead to such limitations. In the field of organic solar cells with rather low charge carrier mobilities, the encounter of two charge carriers has turned out to be the limiting factor for charge carrier recombination. The recombination process strongly depends on the charge carrier mobilities...
June 14, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#18
Analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons is reviewed. Energy bands in NGS correspond to special relativity, the latter is analogous to two-band k.p description for NGS. Maximum electron velocity in NGS is u=(okolo)1x 10^8 cm/s corresponding to the light velocity. An effective mass of electrons in semiconductors is introduced relating their velocity to quasimomentum. This mass depends on energy similarly to the mass of relativistic electrons. In Hg_(1-x)Cd_(x)Te alloys one can reach vanishing energy gap at which electrons and light holes are 3D massless Dirac fermions...
June 13, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#19
Sabyasachi Dasgupta, Thorsten Auth, Gerhard Gompper
Systems with interfaces are abundant in both technological applications and biology. While a fluid interface separates two fluids, membranes separate the inside of vesicles from the outside, the interior of biological cells from the environment, and compartmentalize cells into organelles. The physical properties of interfaces are characterized by interface tension, those of membranes are characterized by bending and stretching elasticity. Amphiphilic molecules like surfactants that are added to a system with two immiscible fluids decrease the interface tension and induce a bending rigidity...
June 13, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#20
Pietro Cortona
The elastic constants of δ-AlOOH have been calculated for applied pressures in the range 0-40 GPa using three exchange-correlation functionals, i.e. PBEsol, TCAsol, and PBE. PBEsol and TCAsol, which describe very well the geometry of this system, give similar results, while the PBE values are smaller, a consequence of the fact that the PBE lattice parameters are too large. In agreement with the experiments, the calculations show that at low pressures the axial compressibility is greater in the b direction and smaller in the c direction, while the opposite is true at high pressure...
June 13, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
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