American Physical Society Acta Medica Okayama 2469-9950 103 2021 Successive destruction of charge density wave states by pressure in LaAgSb2 085134 EN Kazuto Akiba Graduate School of Natural Science and Technology, Okayama University Hiroaki Nishimori Graduate School of Natural Science and Technology, Okayama University Nobuaki Umeshita Graduate School of Natural Science and Technology, Okayama University Tatsuo C. Kobayashi Graduate School of Natural Science and Technology, Okayama University We comprehensively studied the magnetotransport properties of LaAgSb2 under high pressure up to 4 GPa, which showed unique successive charge density wave (CDW) transitions at TCDW1∼210 K and TCDW2∼190 K at ambient pressure. With the application of pressure, both TCDW1 and TCDW2 were suppressed and disappeared at the critical pressures of PCDW1=3.0–3.4 GPa and PCDW2=1.5–1.9 GPa, respectively. At PCDW1, the Hall conductivity showed a steplike increase, which is consistently understood by the emergence of a two-dimensional hollow Fermi surface at PCDW1. We also observed a significant negative magnetoresistance effect when the magnetic field and current were applied parallel to the c axis. The negative contribution was observed in the whole pressure region from 0 to 4 GPa. Shubnikov–de Haas (SdH) oscillation measurements under pressure directly showed the changes in the Fermi surface across the CDW phase boundaries. In P<PCDW2, three major oscillation components, α, β, and γ, were identified, whose frequencies were increased by application of pressure. The increment rate of these frequencies was considerably larger than that expected from the shrinkage of lattice constant, indicating the unignorable band modification under pressure. In the normal metallic phase above P>PCDW1, we observed a single frequency of ∼48 T with a cyclotron effective mass of 0.066m0, whose cross section in the reciprocal space corresponded to only 0.22% of the first Brillouin zone. Besides, we observed another oscillation component with frequency of ∼9.2 T, which is significantly enhanced in the limited pressure range of PCDW2<P<PCDW1. The amplitude of this oscillation was anomalously suppressed in the high-field and low-temperature region, which cannot be explained by the conventional Lifshitz-Kosevich formula. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2643-1564 2 4 2020 Anomalous Hall effect triggered by pressure-induced magnetic phase transition in α-Mn 043090 EN Kazuto Akiba Graduate School of Natural Science and Technology, Okayama University Kaisei Iwamoto Graduate School of Natural Science and Technology, Okayama University Takaaki Sato Graduate School of Natural Science and Technology, Okayama University Shingo Araki Graduate School of Natural Science and Technology, Okayama University Tatsuo C. Kobayashi Graduate School of Natural Science and Technology, Okayama University Recent interest in topological nature in condensed matter physics has revealed the essential role of Berry curvature in the anomalous Hall effect (AHE). However, since a large Hall response originating from Berry curvature has been reported in quite limited materials, the detailed mechanism remains unclear at present. Here, we report the discovery of a large AHE triggered by a pressure-induced magnetic phase transition in elemental α-Mn. The AHE is absent in the noncollinear antiferromagnetic phase at ambient pressure, whereas a large AHE is observed in the weak ferromagnetic phase under high pressure despite the small magnetization of ≈0.02μB/Mn. Our results indicate that the emergence of the AHE in α-Mn is governed by the symmetry of the underlying magnetic structure, providing a direct evidence of a switch between a zero and nonzero contribution of the Berry curvature across the phase boundary. α-Mn can be an elemental and tunable platform to reveal the role of Berry curvature in AHE. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 101 24 2020 Magnetotransport properties of tellurium under extreme conditions 245111 EN Kazuto Akiba Graduate School of Natural Science and Technology, Okayama University Kaya Kobayashi Research Institute for Interdisciplinary Science, Okayama University Tatsuo C. Kobayashi Graduate School of Natural Science and Technology, Okayama University Ryo Koezuka The Institute for Solid State Physics, The University of Tokyo Atsushi Miyake The Institute for Solid State Physics, The University of Tokyo Jun Gouchi The Institute for Solid State Physics, The University of Tokyo Yoshiya Uwatoko The Institute for Solid State Physics, The University of Tokyo Masashi Tokunaga The Institute for Solid State Physics, The University of Tokyo This study investigates the transport properties of a chiral elemental semiconductor tellurium (Te) under magnetic fields and pressure. Application of hydrostatic pressure reduces the resistivity of Te, while its temperature dependence remains semiconducting up to 4 GPa, contrary to recent theoretical and experimental studies. Application of higher pressure causes structural as well as semiconductor-metal transitions. The resulting metallic phase above 4 GPa exhibits superconductivity at 2 K along with a noticeable linear magnetoresistance effect. On the other hand, at ambient pressure, we identified metallic surface states on the as-cleaved (10¯10) surfaces of Te. The nature of these metallic surface states has been systematically studied by analyzing quantum oscillations observed in high magnetic fields. We clarify that a well-defined metallic surface state exists not only on chemically etched samples that were previously reported, but also on as-cleaved ones. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2470-0045 101 3 2020 Lattice Boltzmann method for simulation of wettable particles at a fluid-fluid interface under gravity 033304 EN Yasushi Mino Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hiroyuki Shinto Department of Chemical Engineering, Fukuoka University A computational technique was developed to simulate wettable particles trapped at a fluid-fluid interface under gravity. The proposed technique combines the improved smoothed profile-lattice Boltzmann method (iSP-LBM) for the treatment of moving solid-fluid boundaries and the free-energy LBM for the description of isodensity immiscible two-phase flows. We considered five benchmark problems in two-dimensional systems, including a stationary drop, a wettable particle trapped at a fluid-fluid interface in the absence or presence of gravity, two freely moving particles at a fluid-fluid interface in the presence of gravity (i.e., capillary floatation forces), and two vertically constrained particles at a fluid-fluid interface (i.e., capillary immersion forces). The simulation results agreed well with theoretical estimations, demonstrating the efficacy of the proposed technique. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2470-0045 95 4 2017 Effect of internal mass in the lattice Boltzmann simulation of moving solid bodies by the smoothed-profile method 043309 EN Yasushi Mino Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Hiroyuki Shinto Department of Chemical Engineering, Fukuoka University Shohei Sakai Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University Hideto Matsuyama Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University A computational method for the simulation of particulate flows that can efficiently treat the particle-fluid boundary in systems containing many particles was developed based on the smoothed-profile lattice Boltzmann method (SPLBM). In our proposed method, which we call the improved SPLBM (iSPLBM), for an accurate and stable simulation of particulate flows, the hydrodynamic force on a moving solid particle is exactly formulated with consideration of the effect of internal fluid mass. To validate the accuracy and stability of iSPLBM, we conducted numerical simulations of several particulate flow systems and compared our results with those of other simulations and some experiments. In addition, we performed simulations on flotation of many lightweight particles with a wide range of particle size distribution, the results of which demonstrated the effectiveness of iSPLBM. Our proposed model is a promising method to accurately and stably simulate extensive particulate flows. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 100 21 2019 Resistivity, Seebeck coefficient, and thermal conductivity of platinum at high pressure and temperature 214302 EN Hitoshi Gomi Institute for Planetary Materials, Okayama University Takashi Yoshino Institute for Planetary Materials, Okayama University Platinum (Pt) is one of the most widely used functional materials for high-pressure and high-temperature experiments. Despite the crucial importance of its transport properties, both experimental and theoretical studies are very limited. In this study, we conducted density functional theory calculations on the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of solid face-centered cubic Pt at pressures up to 200 GPa and temperatures up to 4800 K by using the Kubo-Greenwood formula. The thermal lattice displacements were treated within the alloy analogy, which is represented by means of the Korringa-Kohn-Rostoker method with the coherent potential approximation. The electrical resistivity decreases with pressure and increases with temperature. These two conflicting effects yield a constant resistivity of similar to 70 mu Omega cm along the melting curve. Both pressure and temperature effects enhance the thermal conductivity at low temperatures, but the temperature effect becomes weaker at high temperatures. Although the pressure dependence of the Seebeck coefficient is negligibly small at temperatures below similar to 1500 K, it becomes larger at higher temperatures. It requires a calibration of a thermocouple such as Pt-Rh in high-pressure and -temperature experiments. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469990X 4 2 2019 Three-wave resonant interactions and zonal flows in two-dimensional Rossby-Haurwitz wave turbulence on a rotating sphere 024601 EN Kiori Obuse 1Graduate School of Environmental and Life Science, Okayama University Michio Yamada Research Institute for Mathematical Sciences, Kyoto University This paper addresses three-wave resonant interactions of Rossby-Haurwitz waves in two-dimensional turbulence on a rotating sphere. Zonal modes are often omitted from the "resonant wave set" even when they satisfy the conditions for three-wave resonant interactions, as they do not transfer any energy to other modes in a resonant manner. However, the presence of zonal flows induces phase shifts in other modes, and it is not at all clear that their influence is negligible. Since it is expected that three-wave resonant interactions govern the entire dynamics of turbulence if the rotation rate of the sphere is sufficiently high, by analogy with the theorem regarding three-wave resonant interactions of Rossby waves on a beta plane with sufficiently large beta previously proven by Yamada and Yoneda [Physica D 245, 1 (2013)], an appropriate definition of the resonant wave set was determined by comparing the time evolution of several wave sets on a rapidly rotating sphere. It was found that zonal waves of the form Y-l(m=0) exp(i omega t) with odd l, where Y(l)(m )are the spherical harmonics, should be considered for inclusion in the resonant wave set to ensure that the dynamics of the resonant wave set determine the overall dynamics of the turbulence on a rapidly rotating sphere. Consequently, it is suggested that the minimal resonant wave set that must be considered in the discussion of the three-wave interaction of Rossby-Haurwitz waves is the set consisting of nonzonal resonant waves and zonal waves of the form Y-l(0) exp(icot) with odd l. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 24700045 96 4-1 2017 Numerical calculation on a two-step subdiffusion behavior of lateral protein movement in plasma membranes 042410 EN Tomonari Sumi Research Institute for Interdisciplinary Science and Department of Chemistry, Faculty of Science, Okayama University Atsushi Okumoto Department of Computer Science and Engineering, Graduate School of Engineering, Toyohashi University of Technology Hitoshi Goto Department of Computer Science and Engineering, Graduate School of Engineering, Toyohashi University of Technology Hideo Sekino Department of Computer Science and Engineering, Graduate School of Engineering, Toyohashi University of Technology A two-step subdiffusion behavior of lateral movement of transmembrane proteins in plasma membranes has been observed by using single-molecule experiments. A nested double-compartment model where large compartments are divided into several smaller ones has been proposed in order to explain this observation. These compartments are considered to be delimited by membrane-skeleton "fences" and membrane-protein "pickets" bound to the fences. We perform numerical simulations of a master equation using a simple two-dimensional lattice model to investigate the heterogeneous diffusion dynamics behavior of transmembrane proteins within plasma membranes. We show that the experimentally observed two-step subdiffusion process can be described using fence and picket models combined with decreased local diffusivity of transmembrane proteins in the vicinity of the pickets. This allows us to explain the two-step subdiffusion behavior without explicitly introducing nested double compartments. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 24699926 81 6 2010 Spin textures in condensates with large dipole moments 063623 EN J. A. M. Huhtamaki Department of Physics, Okayama University M. Takahashi Department of Physics, Okayama University T. P. Simula Department of Physics, Okayama University T. Mizushima Department of Physics, Okayama University K. Machida Department of Physics, Okayama University We have solved numerically the ground states of a Bose-Einstein condensate in the presence of dipolar interparticle forces using a semiclassical approach. Our motivation is to model, in particular, the spontaneous spin textures emerging in quantum gases with large dipole moments, such as Cr-52 or Dy condensates, or ultracold gases consisting of polar molecules. For a pancake-shaped harmonic ( optical) potential, we present the ground-state phase diagram spanned by the strength of the nonlinear coupling and dipolar interactions. In an elongated harmonic potential, we observe a helical spin texture. The textures calculated according to the semiclassical model in the absence of external polarizing fields are predominantly analogous to previously reported results for a ferromagnetic F = 1 spinor Bose-Einstein condensate, suggesting that the spin textures arising from the dipolar forces are largely independent of the value of the quantum number F or the origin of the dipolar interactions. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 24699950 98 9 2018 Temperature-dependent local structure and superconductivity of BaPd2As2 and SrPd2As2 094525 EN K. Terashima Research Institute for Interdisciplinary Science, Okayama University E. Paris Dipartimento di Fisica, Universitá di Roma “La Sapienza” L. Simonelli CELLS - ALBA Synchrotron Radiation Facility E. Salas-Colera Spanish CRG BM25 Spline, ESRF - The European Synchrotron A. Puri CRG-LISA, ESRF T. Wakita Research Institute for Interdisciplinary Science, Okayama University Y. Yamada Research Institute for Interdisciplinary Science, Okayama University S. Nakano Research Institute for Interdisciplinary Science, Okayama University H. Idei Research Institute for Interdisciplinary Science, Okayama University K. Kudo Research Institute for Interdisciplinary Science, Okayama University M. Nohara Research Institute for Interdisciplinary Science, Okayama University Y. Muraoka Research Institute for Interdisciplinary Science, Okayama University T. Mizokawa Department of Applied Physics, Waseda University T. Yokoya Research Institute for Interdisciplinary Science, Okayama University N. L. Saini Dipartimento di Fisica, Universitá di Roma “La Sapienza” The local structures of 122-type paradium arsenides, namely BaPd2As2 and SrPd2As2, are examined by As K-edge extended x-ray absorption fine structure measurements to find a possible correlation between the variation of their superconducting transition temperature and the local structure. The local atomic distances are found to be consistent with average distances measured by diffraction techniques. The temperature dependence of mean square relative displacements reveal that, while BaPd2As2 is characterized by a local As-Pd soft mode, albeit with larger atomic disorder, SrPd2As2 shows anomalous As-Pd correlations with a kink at similar to 160 K due to hardening by raising temperature. We have discussed implications of these results and possible mechanisms of differing superconducting transition temperature in relation with the structural instability. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 97 2018 Magnetic phase diagram of Sr2-xLaxIrO4 synthesized by mechanical alloying 064425 EN Kazumasa Horigane Research Institute for Interdisciplinary Science, Okayama University M. Fujii Graduate School of Natural Science and Technology, Okayama University H. Okabe Institute of Materials Structure Science/J-PARC Center, KEK K. Kobayashi Research Institute for Interdisciplinary Science, Okayama University R. Horie Research Institute for Interdisciplinary Science, Okayama University H. Ishii Y. F. Liao National Synchrotron Radiation Research Center Y. Kubozono Research Institute for Interdisciplinary Science, Okayama University A. Koda Institute of Materials Structure Science/J-PARC Center, KEK R. Kadono Institute of Materials Structure Science/J-PARC Center, KEK J. Akimitsu Research Institute for Interdisciplinary Science, Okayama University We report the crystal structure and physical properties of Sr2-xLaxIrO4 synthesized by mechanical alloying. The magnetic transition temperature T-N and electrical resistivity decreased with increasing La doping, consistent with previous studies involving single-crystalline samples. We also identified the relationship between T-N and tetragonal distortion (c/a) in this system. This result suggests that the magnetism of the Sr214 system is strongly correlated with its crystal structure. Zero-field muon spin rotation/relaxation studies revealed that short-range antiferromagnetic ordering is realized in Sr1.9La0.1IrO4; also, the spin-glass state is stabilized in the low-temperature region. The Ir moment estimated from the longitudinal field mu SR results is 0.045 mu(B), ten times smaller than that of Sr2IrO4 (similar to 0.4 mu(B)), indicating that electrons are introduced into the Ir atoms. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 97 2018 Enhanced superconducting transition temperatures in the rocksalt-type superconductors In1-xSnxTe (x <= 0.5) 104511 EN Kaya Kobayashi Research Institute for Interdisciplinary Science, Okayama University Yukio Ai Department of Physics, Okayama University Harald O. Jeschke Research Institute for Interdisciplinary Science, Okayama University Jun Akimitsu Research Institute for Interdisciplinary Science, Okayama University We investigate superconductivity in In1-xSnxTe (x <= 0.5) synthesized at high pressures of up to 2 GPa and observe an enhancement of the superconducting transition temperature T-c for increasing tin concentration x. These compounds have not been accessible in rocksalt structure via conventional ambient pressure synthesis. While the lattice constant smoothly increases with x, T-c saturates around x = 0.4. Electronic structure calculations indicate that the Tc modulation is brought on by the change of the density of states in the vicinity of the Fermi energy [N(E-F)]. However, differences between the calculated N(E-F) and the observed electronic specific-heat coefficient indicate that the phonon dispersion plays an important role in the system and that the mechanism of superconductivity may not be the same in the entire doping range. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 97 2018 Local NMR relaxation rates T-1(-1) and T-2(-1) depending on the d-vector symmetry in the vortex state of chiral and helical p-wave superconductors 134507 EN Kenta K. Tanaka Department of Physics, Okayama University Masanori Ichioka Department of Physics, Okayama University Seiichiro Onari Department of Physics, Okayama University Local NMR relaxation rates in the vortex state of chiral and helical p-wave superconductors are investigated by the quasiclassical Eilenberger theory. We calculate the spatial and resonance frequency dependences of the local NMR spin-lattice relaxation rate T-1(-1) and spin-spin relaxation rate T-2(-1). Depending on the relation between the NMR relaxation direction and the d-vector symmetry, the local T-1(-1) and T-2(-1) in the vortex core region show different behaviors. When the NMR relaxation direction is parallel to the d-vector component, the local NMR relaxation rate is anomalously suppressed by the negative coherence effect due to the spin dependence of the odd- frequency s-wave spin-triplet Cooper pairs. The difference between the local T-1(-1) and T-2(-1) in the site-selective NMR measurement is expected to be a method to examine the d-vector symmetry of candidate materials for spin-triplet superconductors. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 01631829 97 10 2018 Pressure-induced superconductivity in AgxBi2-xSe3 104503 EN Tong He Research Institute for Interdisciplinary Science, Okayama University Xiaofan Yang Research Institute for Interdisciplinary Science, Okayama University Takahiro Terao Research Institute for Interdisciplinary Science, Okayama University Takaki Uchiyama Research Institute for Interdisciplinary Science, Okayama University Teppei Ueno Research Institute for Interdisciplinary Science, Okayama University Kaya Kobayashi Research Institute for Interdisciplinary Science, Okayama University Jun Akimitsu Research Institute for Interdisciplinary Science, Okayama University Takafumi Miyazaki Research Laboratory for Surface Science, Okayama University Takumi Nishioka Department of Physical Science and Engineering, Nagoya Institute of Technology Koji Kimura Department of Physical Science and Engineering, Nagoya Institute of Technology Kouichi Hayashi Frontier Research Institute for Materials Science, Nagoya Institute of Technology Naohisa Happo Graduate School of Information Science, Hiroshima City University, Hitoshi Yamaoka RIKEN SPring-8 Center Hirofumi Ishii National Synchrotron Radiation Research Center Yen-Fa Liao National Synchrotron Radiation Research Center Hiromi Ota Advanced Science Research Center, Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University We investigated the pressure dependence of electric transport and crystal structure of Ag-doped Bi2Se3. In the sample prepared by Ag doping of Bi2Se3, the Bi atom was partially replaced by Ag, i.e., Ag0.05Bi1.95Se3. X-ray diffraction patterns of Ag0.05Bi1.95Se3 measured at 0–30 GPa showed three different structural phases, with rhombohedral, monoclinic, and tetragonal structures forming in turn as pressure increased, and structural phase transitions at 8.8 and 24 GPa. Ag0.05Bi1.95Se3 showed no superconductivity down to 2.0 K at 0 GPa, but under pressure, superconductivity suddenly appeared at 11 GPa. The magnetic field (H) dependence of the superconducting transition temperature Tc was measured at 11 and 20.5 GPa, in order to investigate whether the pressure-induced superconducting phase is explained by either p-wave polar model or s-wave model. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 01631829 97 9 2018 Pressure dependence of superconductivity in low- and high-T-c phases of (NH3)(y)NaxFeSe 094505 EN Takahiro Terao Research Institute for Interdisciplinary Science, Okayama University Xiaofan Yang Research Institute for Interdisciplinary Science, Okayama University Xiao Miao Research Institute for Interdisciplinary Science, Okayama University Lu Zheng Research Institute for Interdisciplinary Science, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Takafumi Miyazaki Research Laboratory for Surface science, Okayama University Hitoshi Yamaoka RIKEN SPring-8 Center Hirofumi Ishii National Synchrotron Radiation Research Center Yen-Fa Liao National Synchrotron Radiation Research Center Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University We prepared two superconducting phases, which are called “low-Tc phase” and “high-Tc phase” of (NH3)yNaxFeSe showing Tc’s of 35 and 44 K, respectively, at ambient pressure, and studied the superconducting behavior and structure of each phase under pressure. The Tc of the 35 K at ambient pressure rapidly decreases with increasing pressure up to 10 GPa, and it remains unchanged up to 22 GPa. Finally, superconductivity was not observed down to 1.4 K at 29 GPa, i.e., Tc < 1.4K. The Tc of the 44 K phase also shows a monotonic decrease up to 15 GPa and it weakly decreases up to 25 GPa. These behaviors suggest no pressure-driven high-Tc phase (called “SC-II”) between 0 and 25 GPa for the low-Tc and high-Tc phases of (NH3)yNaxFeSe, differing from the behavior of (NH3)yCsxFeSe,which has a pressure-driven high-Tc phase (SC-II) in addition to the superconducting phase (SC-I) observed at ambient and low pressures. The Tc-c phase diagram for both low-Tc and high-Tc phases shows that the Tc can be linearly scaled with c (or FeSe plane spacing), where c is a lattice constant. The reason why a pressure-driven high-Tc phase (SC-II) was found for neither low-Tc nor high-Tc phases of (NH3)yNaxFeSe is fully discussed, suggesting a critical c value as the key to forming the pressure-driven high-Tc phase (SC-II). Finally, the precise Tc-c phase diagram is depicted using the data obtained thus far from FeSe codoped with a metal and NH3 or amine, indicating two distinct Tc-c lines below c = 17.5A° . No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 1050-2947 82 2 2010 Splitting and oscillation of Majorana zero modes in the p-wave BCS-BEC evolution with plural vortices 023624 EN T. Mizushima Department of Physics, Okayama University K. Machida Department of Physics, Okayama University We investigate how the vortex-vortex separation changes Majorana zero modes in the vicinity of the BCS-BEC (Bose-Einstein condensation) topological phase transition of p-wave resonant Fermi gases. By analytically and numerically solving the Bogoliubov-de Gennes equation for spinless p-wave superfluids with plural vortices, it is demonstrated that the quasiparticle tunneling between neighboring vortices gives rise to the quantum oscillation of the low-lying spectra on the scale of the Fermi wavelength in addition to the exponential splitting. This rapid oscillation, which appears in the weak-coupling regime as a consequence of quantum oscillations of quasiparticle wave functions, disappears in the vicinity of the BCS-BEC topological phase transition. This is understandable from that the wave function of the Majorana zero modes is described by the modified Bessel function in the strong-coupling regime, and thus it becomes spread over the vortex core region. Due to the exponential divergence of the modified Bessel function, the concrete realization of the Majorana zero modes near the topological phase transition requires the neighboring vortices to be separated beyond the length scale defined by the coherence length and the dimensionless coupling constant. All these behaviors are also confirmed by carrying out the full numerical diagonalization of the nonlocal Bogoliubov-de Gennes equation in a two-dimensional geometry. Furthermore, this argument is expanded into the case of three-vortex systems, where a pair of core-bound and edge-bound Majorana states survive at zero-energy state regardless of the vortex separation. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9926 84 1 2011 Textures of F = 2 spinor Bose-Einstein condensates with spin-orbit coupling 011607 EN Takuto Kawakami Department of Physics, Okayama University Takeshi Mizushima Department of Physics, Okayama University Kazushige Machida Department of Physics, Okayama University We study the textures of F = 2 spinor Bose-Einstein condensates (BECs) with spin-orbit coupling (SOC) induced by a synthetic non-Abelian gauge field. On the basis of the analysis of the SOC energy and the numerical calculation of the Gross-Pitaevskii equation, we demonstrate that the textures originate from the helical modulation of the order parameter (OP) due to the SOC. In particular, the cyclic OP consists of two-dimensional lattice textures, such as the hexagonal lattice and the 1/3 vortex lattice, commonly understandable as the two-dimensional network of the helical modulations. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 1050-2947 86 1 2012 Dynamics of two-photon paired superradiance 013812 EN Motohiko Yoshimura Center of Quantum Universe, Faculty of Science, Okayama University N. Sasao Research Core for Extreme Quantum World, Okayama University M. Tanaka Department of Physics, Graduate School of Science, Osaka University We develop for dipole-forbidden transition a dynamical theory of two-photon paired superradiance (PSR). This is a cooperative process characterized by two photons emitted back to back with equal energies. By irradiating the trigger laser from two target ends, with its frequency tuned at the half energy between two levels, a macroscopically coherent state of medium and fields dynamically emerges as time evolves, and a large signal of amplified output occurs with a time delay. The basic semiclassical equations in 1 + 1 space-time dimensions are derived for the field-plus-medium system to describe the space-time evolution of the entire system and are numerically solved to demonstrate the existence of both explosive and weak PSR phenomena in the presence of relaxation terms. The explosive PSR event terminates accompanying a sudden release of most of the energy stored in the target. Our numerical simulations are performed using the vibrational transition X-1 Sigma(+)(g)upsilon = 1 -> 0 of a para-H-2 molecule and taking many different excited atom number densities and different initial coherences between the metastable and the ground states. In an example with a number density close to O(10(21) cm(-3)) and a high initial coherence, the explosive event terminates several nanoseconds after the trigger irradiation, when the phase relaxation time larger than O(10 ns) is taken. After PSR events the system is expected to follow a steady-state solution which is obtained by analytic means and is made of many objects of field condensates endowed with a topological stability. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9926 96 6 2017 Frequency dependence of coherently amplified two-photon emission from hydrogen molecules 063827 EN Hideaki Hara Research Institute for Interdisciplinary Science, Okayama University Yuki Miyamoto Research Institute for Interdisciplinary Science, Okayama University Takahiro Hiraki Research Institute for Interdisciplinary Science, Okayama University Takahiko Masuda Research Institute for Interdisciplinary Science, Okayama University Noboru Sasao Research Institute for Interdisciplinary Science, Okayama University Satoshi Uetake Research Institute for Interdisciplinary Science, Okayama University Akihiro Yoshimi Research Institute for Interdisciplinary Science, Okayama University Koji Yoshimura Research Institute for Interdisciplinary Science, Okayama University Motohiko Yoshimura Research Institute for Interdisciplinary Science, Okayama University We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 mu m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 93 10 2016 Correlation of superconductivity with crystal structure in (NH3)(y)CsxFeSe 104508 EN Lu Zheng Research Laboratory for Surface Science, Okayama University Xiao Miao Research Laboratory for Surface Science, Okayama University Yusuke Sakai Research Laboratory for Surface Science, Okayama University Hidenori Goto Research Laboratory for Surface Science, Okayama University Eri Uesugi Research Laboratory for Surface Science, Okayama University Ritsuko Eguchi Research Laboratory for Surface Science, Okayama University Saki Nishiyama Research Laboratory for Surface Science, Okayama University Kunihisa Sugimoto Japan Synchrotron Radiation Research Institute, SPring-8 Akihiko Fujiwara Department of Nanotechnology for Sustainable Energy, Kwansei Gakuin University Yoshihiro Kubozono Research Centre of New Functional Materials for Energy Production, Storage and Transport, Okayama University The superconducting transition temperature T-c of ammoniated metal-doped FeSe (NH3)(y)MxFeSe (M: metal atom) has been scaled with the FeSe plane spacing, and it has been suggested that the FeSe plane spacing depends on the location of metal atoms in (NH3)(y)MxFeSe crystals. Although the crystal structure of (NH3)(y)LixFeSe exhibiting a high T-c (similar to 44 K) was determined from neutron diffraction, the structure of (NH3)(y)MxFeSe exhibiting a low T-c (similar to 32 K) has not been determined thus far. Here, we determined the crystal structure of (NH3)(y)Cs0.4FeSe (T-c = 33 K) through the Rietveld refinement of the x-ray diffraction (XRD) pattern measured with synchrotron radiation at 30 K. The XRD pattern was analyzed based on two different models, on-center and off-center, under a space group of 14/mmm. In the on-center structure, the Cs occupies the 2a site and the N of NH3 may occupy either the 4c or 2b site, or both. In the off-center structure, the Cs may occupy either the 4c or 2b site, or both, while the N occupies the 2a site. Only an on-center structure model in which the Cs occupies the 2a and the N of NH3 occupies the 4c site provided reasonable results in the Rietveld analysis. Consequently, we concluded that (NH3)(y)Cs0.4FeSe can be assigned to the on-center structure, which produces a smaller FeSe plane spacing leading to the lower T-c. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 94 17 2016 Superconductivity in (NH3)(y)NaxFeSe0.5Te0.5 174505 EN Lu Zheng Research Institute for Interdisciplinary Science, Okayama University Yusuke Sakai Research Institute for Interdisciplinary Science, Okayama University Xiao Miao Research Institute for Interdisciplinary Science, Okayama University Saki Nishiyama Research Institute for Interdisciplinary Science, Okayama University Takahiro Terao Research Institute for Interdisciplinary Science, Okayama University Ritsuko Eguchi, Research Institute for Interdisciplinary Science, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University Na-intercalated FeSe0.5Te0.5 was prepared using the liquid NH3 technique, and a superconducting phase exhibiting a superconducting transition temperature (T-c) as high as 27 K was discovered. This can be called the high-T-c phase since a 21 K superconducting phase was previously obtained in (NH3)(y)NaxFeSe0.5Te0.5. The chemical composition of the high-T-c phase was determined to be (NH3)(0.61(4))Na-0.63(5) Fe0.85Se0.55(3) Te-0.44(2). The x-ray diffraction patterns of both phases show that a larger lattice constant c (i.e., FeSe0.5Te0.5 plane spacing) produces a higher T-c. This behavior is the same as that of metal-doped FeSe, suggesting that improved Fermi-surface nesting produces the higher T-c. The high-T-c phase converted to the low-T-c phase within several days, indicating that it is a metastable phase. The temperature dependence of resistance for both phases was recorded at different magnetic fields, and the critical fields were determined for both phases. Finally, the T-c versus c phase diagram was prepared for the metal-doped FeSe0.5Te0.5, which is similar to that of metal-doped FeSe, although the T-c is lower. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 95 24 2017 Transistor properties of exfoliated single crystals of 2H-Mo(Se1-x Te-x) 2 ( 0 <= x <= 1) 245310 EN Eri Uesugi Research Institute for Interdisciplinary Science, Okayama University Xiao Miao Research Institute for Interdisciplinary Science, Okayama University Hiromi Ota Advanced Science Research Center, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University Field-effect transistors (FETs) were fabricated using exfoliated single crystals of Mo(Se1-x Te-x)(2) with an x range of 0 to 1, and the transistor properties fully investigated at 295 K in four-terminal measurement mode. The chemical composition and crystal structure of exfoliated single crystals were identified by energy-dispersive x-ray spectroscopy (EDX), single-crystal x-ray diffraction, and Raman scattering, suggesting the 2H - structure in all Mo(Se1-x Te-x)(2). The lattice constants of a and c increase monotonically with increasing x, indicating the substitution of Se by Te. When x < 0.4 in a FET with a thin single crystal of Mo(Se1-x Te-x)(2), n-channel FET properties were observed, changing to p-channelor ambipolar operation for x > 0.4. In contrast, the polarity of a thick single-crystal Mo(Se1-x Te-x)(2) FET did not change despite an increase in x. The change of polarity in a thin single-crystal FET was well explained by the variation of electronic structure. The absence of such change in the thick single-crystal FET can be reasonably interpreted based on the large bulk conduction due to naturally accumulated electrons. The mu value in the thin single-crystal FET showed a parabolic variation, with a minimum mu at around x = 0.4, which probably originates from the disorder of the single crystal caused by the partial replacement of Se by Te, i.e., a disorder that may be due to ionic size difference of Se and Te. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 1 2017 Preparation of new superconductors by metal doping of two-dimensional layered materials using ethylenediamine 014502 EN Xiao Miao Research Institute for Interdisciplinary Science, Okayama University Takahiro Terao Research Institute for Interdisciplinary Science, Okayama University Xiaofan Yang Research Institute for Interdisciplinary Science, Okayama University Saki Nishiyama Research Institute for Interdisciplinary Science, Okayama University Takafumi Miyazaki Research Laboratory for Surface Science, Okayama University Hidenori Goto Research Institute for Interdisciplinary Science, Okayama University Yoshihiro Iwasa Department of Applied Physics, The University of Tokyo Yoshihiro Kubozono Research Institute for Interdisciplinary Science, Okayama University We have studied new superconductors prepared by metal doping of two-dimensional (2D) layered materials, FeSe and FeSe0.5Te0.5, using ethylenediamine (EDA). The superconducting transition temperatures (T(c)s) of metal-doped FeSe and metal-doped FeSe0.5Te0.5, i.e., (EDA)(y)MxFeSe and (EDA)(y)MxFeSe0.5Te0.5 (M: Li, Na, and K), were 31-45 K and 19-25 K, respectively. The stoichiometry of each sample was clarified by energy dispersive x-ray (EDX) spectroscopy, and the x-ray powder diffraction pattern indicated a large expansion of lattice constant c, indicating the cointercalation of metal atoms and EDA. The pressure dependence of superconductivity in (EDA)(y)NaxFeSe0.5Te0.5 has been investigated at a pressure of 0-0.8GPa, showing negative pressure dependence in the same manner as (NH3)(y)NaxFeSe0.5Te0.5. The T-c-c phase diagrams of MxFeSe and MxFeSe0.5Te0.5 were drawn afresh from the T-c and c of (EDA)(y)MxFeSe and (EDA)(y)MxFeSe0.5Te0.5, showing that the T-c increases with increasing c but that extreme expansion of c reverses the T-c trend. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 93 14 2016 Composition-induced structural instability and strong-coupling superconductivity in Au1-xPdxTe2 140505 EN Kazutaka Kudo Department of Physics, Okayama University Hiroyuki Ishii Department of Physics, Okayama University Minoru Nohara Research Institute for Interdisciplinary Science, Okayama University The physical properties and structural evolution of the MX2-type solid solution Au1-xPdxTe2 are reported. The end member AuTe2 is a normal metal with a monoclinic distorted CdI2-type structure with preformed Te-Te dimers. A monoclinic-trigonal structural phase transition at a finite temperature occurs upon Pd substitution and is suppressed to zero temperature near x = 0.55, and a superconducting phase with a maximum T-c = 4.65 K emerges. A clear indication of strong-coupling superconductivity is observed near the composition of the structural instability. The competitive relationship between Te-Te dimers and superconductivity is proposed. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 95 8 2017 Ce 4f electronic states of CeO1-xFxBiS2 studied by soft x-ray photoemission spectroscopy 085109 EN Takanori Wakita Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University Kensei Terashima Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University Takahiro Hamada Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University Hirokazu Fujiwara Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University Makoto Minohara Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Masaki Kobayashi Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Koji Horiba Hiroshi Kumigashira Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Galif Kutluk Synchrotron Radiation Center, Hiroshima University Masanori Nagao Center for Crystal Science and Technology, University of Yamanashi Satoshi Watauchi Center for Crystal Science and Technology, University of Yamanashi Isao Tanaka Center for Crystal Science and Technology, University of Yamanashi Satoshi Demura National Institute for Materials Science Hiroyuki Okazaki National Institute for Materials Science Yoshihiko Takano National Institute for Materials Science Yoshikazu Mizuguchi Department of Electrical and Electronic Engineering, Tokyo Metropolitan University Osuke Miura Department of Electrical and Electronic Engineering, Tokyo Metropolitan University Kozo Okada Department of Physics and the Graduate school of Natural Science and Technology, Okayama University Yuji Muraoka Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University Takayoshi Yokoya Research Laboratory for Surface Science and the Graduate School of Natural Science and Technology, Okayama University We use soft x-ray photoemission spectroscopy (SXPES) to investigate Ce 4f electronic states of a new BiS2 layered superconductor CeO1-xFxBiS2, for polycrystalline and single-crystal samples. The Ce 3d spectrum of the single crystal of nominal composition x = 0.7 has no f(0) component and the spectral shape closely resembles the ones observed for Ce trivalent insulating compounds, strongly implying that the CeO layer is still in an insulating state even after the F doping. The Ce 3d-4f resonant SXPES for both polycrystalline and single-crystal samples shows that the prominent peak is located around 1 eV below the Fermi level (E-F) with negligible spectral intensity at EF. The F-concentration dependence of the valence band spectra for single crystals shows the increases of the degeneracy in energy levels and of the interaction between Ce 4f and S 3p states. These results give insight into the nature of the CeO1-xFx layer and the microscopic coexistence of magnetism and superconductivity in CeO1-xFxBiS2. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 4 2017 Evolution of the remnant Fermi-surface state in the lightly doped correlated spin-orbit insulator Sr2-xLaxIrO4 041106 EN Kensei Terashima Research Institute for Interdisciplinary Science, Okayama University M. Sunagawa Graduate School of Natural Sciences, Okayama University H. Fujiwara Graduate School of Natural Sciences, Okayama University T. Fukura M. Fujii Graduate School of Natural Sciences, Okayama University K. Okada Aoyama Gakuin University K. Horigane Research Institute for Interdisciplinary Science, Okayama University K. Kobayashi Research Institute for Interdisciplinary Science, Okayama University R. Horie Research Institute for Interdisciplinary Science, Okayama University J. Akimitsu Research Institute for Interdisciplinary Science, Okayama University E. Golias Helmholtz-Zentrum Berlin für Materialien und Energie D. Marchenko Helmholtz-Zentrum Berlin für Materialien und Energie A. Varykhalov Helmholtz-Zentrum Berlin für Materialien und Energie N. L. Saini Dipartimento di Fisica, Universitá di Roma “La Sapienza T. Wakita Research Institute for Interdisciplinary Science, Okayama University Y. Muraoka Research Institute for Interdisciplinary Science, Okayama University T. Yokoya Research Institute for Interdisciplinary Science, Okayama University The electronic structure of the lightly electron-doped correlated spin-orbit insulator Sr2IrO4 has been studied by angle-resolved photoelectron spectroscopy. We have observed the coexistence of a lower Hubbard band and an in-gap band; the momentum dependence of the latter traces that of the band calculations without on-site Coulomb repulsion. The in-gap state remained anisotropically gapped in all observed momentum areas, forming a remnant Fermi-surface state, evolving towards the Fermi energy by carrier doping. These experimental results show a striking similarity with those observed in deeply underdoped cuprates, suggesting the common nature of the nodal liquid states observed in both compounds. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 2 2017 Spin pumping into superconductors: A new probe of spin dynamics in a superconducting thin film 024414 EN Masashi Inoue Department of Physics, Okayama University Masanori Ichioka Research Institute for Interdisciplinary Science, Okayama University Hiroto Adachi Research Institute for Interdisciplinary Science, Okayama University Spin pumping refers to the microwave-driven spin current injection from a ferromagnet into the adjacent target material. We theoretically investigate the spin pumping into superconductors by fully taking account of impurity spin-orbit scattering that is indispensable to describe diffusive spin transport with finite spin diffusion length. We calculate temperature dependence of the spin pumping signal and show that a pronounced coherence peak appears immediately below the superconducting transition temperature Tc, which survives even in the presence of the spin-orbit scattering. The phenomenon provides us with a new way of studying the dynamic spin susceptibility in a superconducting thin film. This is contrasted with the nuclear magnetic resonance technique used to study a bulk superconductor. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 10 2017 Spin-singlet superconductivity in the doped topological crystalline insulator Sn0.96In0.04Te 104502 EN Satoki Maeda Department of Physics, Okayama University Ryohei Hirose Department of Physics, Okayama University Kazuaki Matano Department of Physics, Okayama University Mario Novak Institute of Scientific and Industrial Research, Osaka University Yoichi Ando Physics Institute II, University of Cologne Guo-qing Zheng Department of Physics, Okayama University The In-doped topological crystalline insulator Sn1－x InxTe is a candidate for a topological superconductor, where a pseudo-spin-triplet state has been proposed. To clarify the spin symmetry of Sn1－x InxTe, we perform 125Te-nuclear magnetic resonance (NMR) measurements in polycrystalline samples with 0 x 0.15. The penetration depth calculated from the NMR line width is T independent below half the superconducting transition temperature (Tc) in polycrystalline Sn0.96In0.04Te, which indicates a fully opened superconducting gap. In this sample, the spin susceptibility measured by the spin Knight shift (Ks) at an external magnetic field of μ0H0 = 0.0872 T decreases below Tc, and Ks(T = 0)/Ks(T = Tc) reaches 0.36 ± 0.10, which is far below the limiting value 2/3 expected for a spin-triplet state for a cubic crystal structure. Our result indicates that polycrystalline Sn0.96In0.04Te is a spin-singlet superconductor. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 93 9 2016 Site-selective NMR for odd-frequency Cooper pairs around vortex in chiral p -wave superconductors 094507 EN Kenta K. Tanaka Department of Physics, Okayama University Masanori Ichioka Department of Physics, Okayama University Seiichiro Onari Department of Physics, Okayama University In order to identify the pairing symmetry with chirality, we study site-selective NMR in chiral p-wave superconductors. We calculate local nuclear relaxation rate T-1(-1) in the vortex lattice state by Eilenberger theory, including the applied magnetic field dependence. We find that T-1(-1) in the NMR resonance line shape is different between two chiral states p +/-(= p(x)+/- ip(y)), depending on whether the chirality is parallel or antiparallel to the vorticity. Anomalous suppression of T-1(-1) occurs around the vortex core in the chiral p(-) wave due to the negative coherence term coming from the odd-frequency s-wave Cooper pair induced around the vortex with Majorana state. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 95 6 2017 Locking of length scales in two-band superconductors 064512 EN Masanori Ichioka Department of Physics, RIIS, Okayama University V. G. Kogan Ames Laboratory-DOE and Department of Physics and Astronomy, Iowa State University J. Schmalian Institut für Theorie der Kondensierten Materie und Institut für Festkörperphysik, Karlsruher Institut für Technologie A model of a clean two-band s-wave superconductor with cylindrical Fermi surfaces, different Fermi velocities v(1),(2), and a general 2x2 coupling matrix V-alpha beta is used to study the order parameter distribution in vortex lattices. The Eilenberger weak coupling formalism is used to calculate numerically the spatial distributions of the pairing amplitudes Delta(1) and Delta(2) of the two bands for vortices parallel to the Fermi cylinders. For generic values of the interband coupling V-12, it is shown that, independently of the couplings V-alpha beta, of the ratio v(1)/v(2), of the temperature, and the applied field, the length scales of spatial variation of Delta(1) and of Delta(2) are the same within the accuracy of our calculations. The only exception from this single length-scale behavior is found for V-12 << V-11, i.e., for nearly decoupled bands. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 95 13 2017 Spin-polarized local density of states in the vortex state of helical p -wave superconductors 134502 EN Kenta K. Tanaka Department of Physics, Okayama University Masanori Ichioka Department of Physics, Okayama University Seiichiro Onari Department of Physics, Okayama University Properties of the vortex state in helical p-wave superconductor are studied by the quasiclassical Eilenberger theory. We confirm the instability of the helical p-wave state at high fields and that the spin-polarized local density of states M(E,r) appears even when Knight shift does not change. This is because the vorticity couples to the chirality of up-spin pair or down-spin pair of the helical state. In order to identify the helical p-wave state at low fields, we investigate the structure of the zero-energy M(E = 0,r) in the vortex states, and also the energy spectra of M(E,r). No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 96 9 2017 Pair breaking of multigap superconductivity under parallel magnetic fields in the electric-field-induced surface metallic state 094522 EN Masahiro Nabeta Department of Physics, Okayama University Kenta K. Tanaka Department of Physics, Okayama University Seiichiro Onari Department of Physics, Okayama University Masanori Ichioka Department of Physics, Okayama University The roles of paramagnetic and diamagnetic pair-breaking effects in superconductivity in the electric-field-induced surface metallic state are studied using the Bogoliubov–de Gennes equation when magnetic fields are applied parallel to the surface. The multigap states of the subbands are related to the depth dependence and the magnetic field dependence of the superconductivity. In the Fermi-energy density of states and the spin density, subband contributions successively appear from higher-level subbands with increasing magnetic fields. The characteristic magnetic field dependence may be a key feature to identify the multigap structure of the surface superconductivity. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 2469-9950 96 9 2017 In-plane anisotropy of transport coefficients in electronic nematic states: Universal origin of nematicity in Fe-based superconductors 094527 EN Seiichiro Onari Department of Physics, Okayama University Hiroshi Kontani Department of Physics, Nagoya University The origin of the electronic nematicity and its remarkable material dependence are famous longstanding unsolved issues in Fe-based superconductors. To attack these issues, we focus on the in-plane anisotropy of the resistivity: In the nematic state in FeSe, the relationp(x) >p(y) holds, whereP(x)(y) is the resistivity along the longer (shorter) Fe-Fe axis. In contrast, the opposite anisotropy p(x) < p(y) is realized in other undoped Fe-based superconductors. Such nontrivial material dependence is naturally explained in terms of the strongly orbitaldependent inelastic quasiparticle scattering realized in the orbital-ordered state. The opposite anisotropy between FeSe (p(x) >p(y)) and other undoped compounds (P-x < P-y) reflects the difference in the number of hole pockets. We also explain the large in-plane anisotropy of the thermoelectric power in the nematic state. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 1539-3755 91 1 2015 Reply to “Comment on ‘Spontaneous liquid-liquid phase separation of water’ ” 016302 EN Takuma Yagasaki Department of Chemistry, Faculty of Science, Okayama University Masakazu Matsumoto Department of Chemistry, Faculty of Science, Okayama University Hideki Tanaka Department of Chemistry, Faculty of Science, Okayama University Two different scenarios have been proposed on the phase separation occurring in the deeply supercooled liquid water. We discuss what we can derive from our simulation results for the two scenarios and propose a way for future investigation. We also demonstrate that the phase separation in the supercooled liquid water looks like the separation of liquid water and vapor just below the conventional critical point. No potential conflict of interest relevant to this article was reported.

American Physical Society Acta Medica Okayama 0031-9007 115 19 2015 Chiral Ordering in Supercooled Liquid Water and Amorphous Ice 197801 EN Masakazu Matsumoto Takuma Yagasaki Hideki Tanaka The emergence of homochiral domains in supercooled liquid water is presented using molecular dynamics simulations. An individual water molecule possesses neither a chiral center nor a twisted conformation that can cause spontaneous chiral resolution. However, an aggregation of water molecules will naturally give rise to a collective chirality. Such homochiral domains possess obvious topological and geometrical orders and are energetically more stable than the average. However, homochiral domains cannot grow into macroscopic homogeneous structures due to geometrical frustrations arising from their icosahedral local order. Homochiral domains are the major constituent of supercooled liquid water and the origin of heterogeneity in that substance, and are expected to be enhanced in low-density amorphous ice at lower temperatures. No potential conflict of interest relevant to this article was reported.