Unconventional superconductivity on a topological insulator (2009)
Linder, Jacob, Tanaka, Yukio, Yokoyama, Takehito, Sudbø, Asle, Nagaosa, Naoto
We study proximity-induced superconductivity on the surface of a topological insulator (TI), focusing on unconventional pairing. We find that the excitation spectrum becomes gapless for any...
Electrically controlled superconducting states at the heterointerface SrTiO$_3$/LaAlO$_3$ (2009)
Yada, Keiji, Onari, Seiichiro, Tanaka, Yukio, Inoue, Jun-ichiro
We study the symmetry of Cooper pair in a two-dimensional Hubbard model with the Rashba-type spin-orbit interaction as a minimal model of electron gas generated at a heterointerface of...
Anomalous magnetoresistance on the topological surface (2009)
Yokoyama, Takehito, Tanaka, Yukio, Nagaosa, Naoto
We investigate charge transport in two-dimensional ferromagnet/feromagnet junction on a topological insulator. The conductance across the interface depends sensitively on the directions of the...
Tanaka, Yukio, Yokoyama, Takehito, Nagaosa, Naoto
We study theoretically charge transport properties of normal metal (N) / ferromagnet insulator (FI) / superconductor (S) junction and S/FI/S junction formed on the surface of three-dimensional...
Theory of charge transport in ferromagnetic semiconductor/s-wave superconductor junction (2009)
Mizuno, Yoshihiro, Yokoyama, Takehito, Tanaka, Yukio
We study tunneling conductance in ferromagnetic semiconductor/insulator/s-wave superconductor junction where Rashba spin-orbit interaction (RSOI) and exchange field are taken into account in the...
Yokoyama, Takehito, Ichioka, Masanori, Tanaka, Yukio
We investigate pairing symmetry in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) vortex state and vortex lattice, and explain the electronic structure in these states in terms of pairing symmetry. We...
Interacting two helical edge modes in quantum spin Hall systems (2009)
We study theoretically the two interacting one-dimensional helical modes at the edges of the quantum spin Hall systems. A new type of inter-edge correlated liquid (IECL) without the spin gap is...
Silaev, Mihail A., Yokoyama, Takehito, Linder, Jacob, Tanaka, Yukio, Sudb\o, Asle
We consider different effects that arise when time-reversal symmetry breaking superconductors are subjected to an external magnetic field, thus rendering the superconductor to be in the mixed state....
Surface DOS of s+-wave in two-band model (2009)
Onari, Seiichiro, Tanaka, Yukio
We calculate surface density of state (SDOS) of s+-wave Cooper pair in two-band superconductor model, where gap functions have different signs between two bands. We find that Andreev bound state...
Giant spin rotation in the normal metal/quantum spin Hall junction (2009)
Yokoyama, Takehito, Tanaka, Yukio, Nagaosa, Naoto
We study theoretically reflection problem in the junction between a normal metal and an insulator characterized by a parameter $M$, which is a usual insulator for $M>0$ or a quantum spin Hall system...
Shigeta, Keisuke, Onari, Seiichiro, Yada, Keiji, Tanaka, Yukio
In order to clarify whether the odd-frequency superconductivity can be realized or not, we study a quasi-one-dimensional triangular lattice in the Hubbard model using the random phase approximation...
Anomalous Transport through the p-Wave Superconducting Channel in the 3-K Phase of Sr_2RuO_4 (2008)
Kambara, Hiroshi, Kashiwaya, Satoshi, Yaguchi, Hiroshi, Asano, Yasuhiro, Tanaka, Yukio, Maeno, Yoshiteru
Using microfabrication techniques, we extracted individual channels of 3-kelvin (3-K) phase superconductivity in Sr_2RuO_4-Ru eutectic systems and confirmed odd-parity superconductivity in the 3-K...
Aizawa, Hirohito, Kuroki, Kazuhiko, Yokoyama, Takehito, Tanaka, Yukio
We study the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of spin fluctuation mediated pairing, and focus on the effect of coexisting charge fluctuations. We find that (i) consecutive transitions...
Strongly spin-polarized current generated in a Zeeman-split unconventional superconductor (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Sudbø, Asle
We consider a thin-film normal- metal/superconductor junction in the presence of an externally applied in-plane magnetic field for several symmetries of the superconducting order parameter. For...
Electron transport in a ferromagnet-superconductor junction on graphene (2008)
Asano, Yasuhiro, Yoshida, Toshihiro, Tanaka, Yukio, Golubov, Alexander A.
In a usual ferromagnet connected with a superconductor, the exchange potential suppresses the superconducting pairing correlation. We show that this common knowledge does not hold in a...
Strongly spin-polarized current generated in Zeeman-split unconventional superconductors (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Sudbø, Asle
We consider a thin-film normal metal/superconductor junction in the presence of an externally applied in-plane magnetic field for several symmetries of the superconducting order parameter. For p-wave...
Topological spin-current in non-centrosymmetric superconductors (2008)
Tanaka, Yukio, Yokoyama, Takehito, Balatsky, Alexander V., Nagaosa, Naoto
We study the spin transport properties of the non-centrosymmetric superconductor with time-reversal-symmetry where spin-triplet $(p_{x} \pm i p_{y})$-wave and spin-singlet s-wave pair potential can...
A Microscopic Theory of Odd-freqeuncy Pairing in the Two-dimensional Extended Hubbard Model (2008)
Yada, Keiji, Onari, Seiichiro, Tanaka, Yukio, Miyake, Kazumasa
We present a microscopic theory of fluctuation-mediated pairing mechanism in a two-dimensional extended Hubbard model. In contrast to conventional wisdom, odd-frequency spin-triplet pairing can be...
Shape of Cooper pairs in a normal-metal/superconductor junction (2008)
Tanaka, Yukio, Asano, Yasuhiro, Golubov, Alexander A.
In s-wave superconductors the Cooper pair wave function is isotropic in momentum space. This property may also be expected for Cooper pairs entering a normal metal from a superconductor due to the...
Chirality Sensitive Effect on Surface States in Chiral p-Wave Superconductors (2008)
Yokoyama, Takehito, Iniotakis, Christian, Tanaka, Yukio, Sigrist, Manfred
We study the local density of states at the surface of a chiral p-wave superconductor in the presence of a weak magnetic field. As a result, the formation of low-energy Andreev bound states is either...
Quantum transport in a normal metal/odd-frequency superconductor junction (2008)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Asano, Yasuhiro, Sudbø, Asle
Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu_2Si_2 and CeRhIn_5. Motivated by this, we present a study of the...
Aizawa, Hirohito, Kuroki, Kazuhiko, Tanaka, Yukio
We study the effect of the magnetic field (Zeeman splitting) on spin triplet superconductivity. We show generally that the enhancement of spin triplet pairing mediated by coexisting 2k_F spin and...
Kuroki, Kazuhiko, Onari, Seiichiro, Arita, Ryotaro, Usui, Hidetomo, Tanaka, Yukio, Kontani, Hiroshi, ...
For a newly discovered iron-based high $T_c$ superconductor LaFeAsO$_{1-x}$F$_x$, we have constructed a minimal model, where inclusion of all the five Fe $d$ bands is found to be necessary....
Theory of pairing symmetry inside the Abrikosov vortex core (2008)
Yokoyama, Takehito, Tanaka, Yukio, Golubov, Alexander A.
We show that the Cooper pair wave function at the center of an Abrikosov vortex with vorticity m has a different parity with respect to frequency from that in the bulk if m is an odd number, while it...
Electron transport in a ferromagnet-superconductor junction on graphene (2008)
Asano, Yasuhiro, Yoshida, Toshihiro, Tanaka, Yukio, Golubov, Alexander A.
In a usual ferromagnet connected with a superconductor, the exchange potential suppresses the superconducting pairing correlation. We show that this common knowledge does not hold in a...
Shape of Cooper pairs in a normal-metal/superconductor junction (2008)
Tanaka, Yukio, Asano, Yasuhiro, Golubov, Alexander A.
In s-wave superconductors the Cooper pair wave function is isotropic in momentum space. This property may also be expected for Cooper pairs entering a normal metal from a superconductor due to the...
Quantum transport in a normal metal/odd-frequency superconductor junction (2007)
Linder, Jacob, Yokoyama, Takehito, Tanaka, Yukio, Asano, Yasuhiro, Sudb\o, Asle
Recent experimental results indicate the possible realization of a bulk odd-frequency superconducting state in the compounds CeCu$_2$Si$_2$, and CeRhIn$_5$. Motivated by this, we present a study of...
Odd-frequency pairs and Josephson current through a strong ferromagnet (2007)
Asano, Yasuhiro, Sawa, Yuki, Tanaka, Yukio, Golubov, Alexander A.
We study Josephson current in superconductor/diffusive ferromagnet/superconductor junctions by using the recursive Green function method. When the exchange potential in a ferromagnet is sufficiently...
Predominant Magnetic States in Hubbard Model on Anisotropic Triangular Lattices (2007)
Watanabe, Tsutomu, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro
Using an optimization variational Monte Carlo method, we study the half-filled-band Hubbard model on anisotropic triangular lattices, as a continuation of the preceding study [J. Phys. Soc. Jpn 75,...
Chirality sensitive effect on surface states in chiral p-wave superconductors (2007)
Yokoyama, Takehito, Iniotakis, Christian, Tanaka, Yukio, Sigrist, Manfred
We study the local density of states at the surface of a chiral p-wave superconductor in the presence of a weak magnetic field. As a result, the formation of low-energy Andreev bound states is either...
Spin-Dependent Mass Enhancement under Magnetic Field in the Periodic Anderson Model (2007)
Onari, Seiichiro, Kontani, Hiroshi, Tanaka, Yukio
In order to study the mechanism of the mass enhancement in heavy fermion compounds in the presence of magnetic field, we study the periodic Anderson model using the fluctuation exchange...
Theory of pairing symmetry inside the Abrikosov vortex core (2007)
Yokoyama, Takehito, Tanaka, Yukio, Golubov, Alexander A.
We show that the Cooper pair wave function at the center of an Abrikosov vortex with vorticity m has different parity with respect to frequency from that in the bulk if m is an odd number and has the...
Theory of macroscopic quantum tunneling in high-T_c c-axis Josephson junctions (2007)
Yokoyama, Takehito, Kawabata, Shiro, Kato, Takeo, Tanaka, Yukio
We study macroscopic quantum tunneling (MQT) in c-axis twist Josephson junctions made of high-Tc superconductors in order to clarify the influence of the anisotropic order parameter symmetry (OPS) on...
Conductance spectroscopy of spin-triplet superconductors. (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi
We propose a novel experiment to identify the symmetry of superconductivity on the basis of theoretical results for differential conductance of a normal metal connected to a superconductor. The...
Conductance Spectroscopy of Spin-Triplet Superconductors (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi
We propose a novel experiment to identify the symmetry of superconductivity on the basis of theoretical results for differential conductance of a normal metal connected to a superconductor. The...
Anomalous Josephson Effect between Even- and Odd-Frequency Superconductors (2007)
Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi, Ueda, Masahito
We demonstrate that, contrary to standard wisdom, the lowest-order Josephson coupling is possible between odd- and even-frequency superconductors. The origin of this effect is the induced odd-...
Odd-frequency Pairs and Josephson Current through a Strong Ferromagnet (2007)
Asano, Yasuhiro, Sawa, Yuki, Tanaka, Yukio, Golubov, Alexander A.
We study Josephson current in superconductor / diffusive ferromagnet /superconductor junctions by using the recursive Green function method. When the exchange potential in a ferromagnet is...
Yokoyama, Takehito, Onari, Seiichiro, Tanaka, Yukio
We study Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of superconductors with and without inversion symmetry based on the Hubbard model on the square lattice near half-filling, using the random...
Aizawa, Hirohito, Kuroki, Kazuhiko, Tanaka, Yukio
We study the effect of the magnetic field (Zeeman splitting) on the triplet pairing. We show generally that the enhancement of spin triplet pairing mediated by coexisting $2k_F$ spin and $2k_F$...
Theory of Macroscopic Quantum Tunneling in High-T_c c-Axis Josephson Junctions (2007)
Yokoyama, Takehito, Kawabata, Shiro, Kato, Takeo, Tanaka, Yukio
We study macroscopic quantum tunneling (MQT) in c-axis twist Josephson junctions made of high-T_c superconductors in order to clarify the influence of the anisotropic order parameter symmetry (OPS)...
Conductance Spectroscopy of Spin-triplet Superconductors (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi
We propose a novel experiment to identify the symmetry of superconductivity on the basis of theoretical results for differential conductance of a normal metal connected to a superconductor. The...
Enhanced triplet superconductivity in noncentrosymmetric systems (2007)
Yokoyama, Takehito, Onari, Seiichiro, Tanaka, Yukio
We study pairing symmetry of noncentrosymmetric superconductors based on the extended Hubbard model on the square lattice near half-filling, using the random phase approximation. We show that d+...
Enhanced triplet superconductivity in noncentrosymmetric systems (2007)
Yokoyama, Takehito, Onari, Seiichiro, Tanaka, Yukio
We study pairing symmetry of noncentrosymmetric superconductors based on the extended Hubbard model on square lattice near half-filling, using the random phase approximation. We show that d+f-wave...
Josephson Effect due to Odd-Frequency Paris in Diffusive Half Metals (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A.
Motivated by a recent experiment [Keizer et al., Nature (London) 439, 825 (2006)], we study the Josephson effect in superconductor/diffusive half metal/superconductor junctions using the recursive...
Unified Origin for the 3D Magnetism and Superconductivity in NaxCoO2 (2007)
Kuroki, Kazuhiko, Ohkubo, Shuhei, Nojima, Takumi, Arita, Ryotaro, Onari, Seiichiro, Tanaka, Yukio
We analyze the origin of the three-dimensional (3D) magnetism observed in nonhydrated Na-rich NaxCoO2 within an itinerant spin picture using a 3D Hubbard model. The origin is identified as the 3D...
Theory of tunneling spectroscopy in the larkin-ovchinnikov state (2007)
Tanaka, Yukio, Asano, Yasuhiro, Ichikawa, Masanori, Kashiwaya, Satoshi
We present a theory of tunneling spectroscopy for normal metal/Larkin-Ovchinnikov state junctions in which the spatial periodic modulation in the pair potential amplitude is taken into account. The...
Theory of Tunneling Spectroscopy in the Larkin-Ovchinnikov State (2007)
Tanaka, Yukio, Asano, Yasuhiro, Ichioka, Masanori, Kashiwaya, Satoshi
We present a theory of tunneling spectroscopy for normal metal/Larkin-Ovchinnikov state junctions in which the spatial periodic modulation in the pair potential amplitude is taken into account. The...
Theory of Macroscopic Quantum Tunneling and Dissipation in High-Tc Josephson Junctions (2007)
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio, Kato, Takeo, Golubov, Alexander A.
We have investigated macroscopic quantum tunneling (MQT) in in-plane high-Tc superconductor Josephson junctions and the influence of the nodal-quasiparticle and the zero energy bound states (ZES) on...
Josephson Effect due to Odd-Frequency Pairs in Diffusive Half Metals (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A.
Motivated by a recent experiment [Keizer et al., Nature (London) 439, 825 (2006)], we study the Josephson effect in superconductor/diffusive half metal/superconductor junctions using the recursive...
Conductance Spectroscopy of Spin-Triplet Superconductors (2007)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi
We propose a novel experiment to identify the symmetry of superconductivity on the basis of theoretical results for differential conductance of a normal metal connected to a superconductor. The...
Anomalous Josephson Effect between Even- and Odd-Frequency Superconductors (2007)
Tanaka, Yukio, Golubov, Alexander A., Kashiwaya, Satoshi, Ueda, Masahito
We demonstrate that, contrary to standard wisdom, the lowest-order Josephson coupling is possible between odd- and even-frequency superconductors. The origin of this effect is the induced odd-...
Quantitative model for the ICR product in d-wave Josephson junctions (2007)
Yokoyama, Takehito, Sawa, Yuki, Tanaka, Yukio, Golubov, Alexander A., Maeda, Atsutaka, Fujimaki, Akira
We study theoretically the Josephson effect in d-wave superconductor/diffusive normal metal/insulator/diffusive normal metal/d-wave superconductor (D/DN/I/DN/D) junctions. This model aims to describe...
Macroscopic quantum dynamics of π junctions with ferromagnetic insulators (2006)
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio, Alexander A., Golubov
We theoretically investigate the macroscopic quantum dynamics of a π junction with a superconductor (S) and a multiferroic material or a ferromagnetic insulator (FI). By deriving the effective...
Shigeta, Iduru, Tanaka, Yukio, Ichikawa, Fusao, Asano, Yasuhiro
We propose a new approach of smearing origins of a zero-bias conductance peak (ZBCP) in high-Tc superconductor tunnel junctions through the analysis based on the circuit theory for a d-wave pairing...
A unified origin for the 3D magnetism and superconductivity in Na$_x$CoO$_2$ (2006)
Kuroki, Kazuhiko, Ohkubo, Shuhei, Nojima, Takumi, Arita, Ryotaro, Onari, Seiichiro, Tanaka, Yukio
We analyze the origin of the three dimensional (3D) magnetism observed in nonhydrated Na-rich Na$_x$CoO$_2$ within an itinerant spin picture using a 3D Hubbard model. The origin is identified as the...
Josephson Effect due to Odd-frequency Pairs in Diffusive Half Metals (2006)
Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander
The Josephson effect in superconductor / diffusive ferromagnet / superconductor (SFS) junctions is studied using the recursive Green function method in the regime of large exchange energy in a...
Macroscopic quantum dynamics of pi-junctions with ferromagnetic insulators (2006)
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio, Golubov, Alexander A.
We theoretically investigate the macroscopic quantum dynamics of a pi junction with a superconductor (S) and a multiferroic material or a ferromagnetic insulator (FI). By deriving the effective...
Anomalous Josephson effect in p-wave dirty junctions (2006)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi
The Josephson effect in p-wave superconductor / diffusive normal metal / p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude...
Yokoyama, Hisatoshi, Ogata, Masao, Tanaka, Yukio
Mechanisms of Mott transitions and dx2-y2-wave superconductivity (SC) are studied in the half-filled-band Hubbard model on square lattices with a diagonal hopping term (t'), using an optimization (or...
Onari, Seiichiro, Kontani, Hiroshi, Tanaka, Yukio
It is known that various transport coefficients strongly deviate from conventional Fermi-liquid behaviors in many electron systems which are close to antiferromagnetic (AF) quantum critical points...
Anomalous Josephson Effect in p-Wave Dirty Junctions (2006)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi, 浅野, 泰寛
The Josephson effect in p-wave superconductor/diffusive normal metal/p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude larger...
Anomalous Josephson Effect in p-Wave Dirty Junctions (2006)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi
The Josephson effect in p-wave superconductor/diffusive normal metal/p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude larger...
Anomalous Josephson Effect in p-Wave Dirty Junctions (2006)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi
The Josephson effect in p-wave superconductor/diffusive normal metal/p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude larger...
Anomalous Josephson Effect in ρ-Wave Dirty Junctions (2006)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi
The Josephson effect in p-wave superconductor/diffusive normal metal/p-wave superconductor junctions is studied theoretically. Amplitudes of Josephson currents are several orders of magnitude larger...
Watanabe, Tsutomu, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro
A half-filled-band Hubbard model on an anisotropic triangular lattice (t in two bond directions and t' in the other) is studied using an optimization variational Monte Carlo method, to consider the...
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Asano, Yasuhiro, Tanaka, Yukio
This Letter theoretically discusses quasiparticle states and nuclear spin relaxation rates $T_1^{-1}$ in a quasi-one-dimensional superconductor (TMTSF)$_2$PF$_6$ under a magnetic field applied...
Asano, Yasuhiro, Tanaka, Yukio, Yokoyama, Takehito, Kashiwaya, Satoshi
The Josephson effect in superconductor/diffusive-normal-metal/superconductor junctions is studied numerically by using the recursive Green function method. In superconductors, we consider...
Asano, Yasuhiro, Tanaka, Yukio, Yokoyama, Takehito, Kashiwaya, Satoshi
The Josephson effect in superconductor/diffusive-normal-metal/superconductor junctions is studied numerically by using the recursive Green function method. In superconductors, we consider...
Asano, Yasuhiro, Tanaka, Yukio, Yokoyama, Takehito, Kashiwaya, Satoshi
The Josephson effect in superconductor/diffusive-normal-metal/superconductor junctions is studied numerically by using the recursive Green function method. In superconductors, we consider...
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Tanaka, Yukio, 瀧川, 光明
The electronic structure around an impurity in spin-triplet p-wave superconductors is studied by the Bogoliubov–de Gennes theory on a tight-binding model, where we have chosen sin px+i sin py-wave...
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Tanaka, Yukio
The electronic structure around an impurity in spin-triplet p-wave superconductors is studied by the
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Tanaka, Yukio
The electronic structure around an impurity in spin-triplet p-wave superconductors is studied by the
Onari, Seiichiro, Kontani, Hiroshi, Tanaka, Yukio
It is known that various transport coefficients strongly deviate from conventional Fermi-liquid behaviors in many electron systems which are close to antiferromagnetic (AF) quantum critical points...
Extended s-wave pairing originating from the $a_{1g}$ band in Na$_x$CoO$_2\cdot y$ H$_2$O (2005)
Kuroki, Kazuhiko, Onari, Seiichiro, Tanaka, Yukio, Arita, Ryotaro, Nojima, Takumi
Motivated by recent experiments and band calculation results, we investigate the possibility of superconductivity originating from the $a_{1g}$ band of Na$_x$CoO$_2\cdot y$H$_2$O assuming the absence...
Decoherence of Phase Qubit using High-Tc Superconductor (2005)
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio
We discuss how to make use of high-Tc d-wave Josephson junctions in the construction of a phase qubit. We especially focus on the effect of the quasiparticle dissipation and the zero energy bound...
Watanabe, Tsutomu, Miyata, Takafumi, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro
Applying a variational Monte Carlo method to a two-dimensional t-J model, we study the nonmonotonic d_{x^2-y^2}-wave superconductivity, observed by Raman scattering and ARPES experiments in the...
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Tanaka, Yukio
The electronic structure around an impurity in spin-triplet p-wave superconductors is studied by the Bogoliubov-de Gennes theory on a tight-binding model, where we have chosen sin p(x)+i sin...
Takigawa, Mitsuaki, Ichioka, Masanori, Kuroki, Kazuhiko, Tanaka, Yukio
The electronic structure around an impurity in spin triplet p-wave superconductors is studied by the Bogoliubov-de Gennes theory on a tight-binding model, where we have chosen $\sin{p_x}{+}{\rm...
Kuroki, Kazuhiko, Tanaka, Yukio
We investigate the effect of interchain repulsive interaction on the pairing symmetry competition in quasi-one-dimensional organic superconductors (TMTSF)$_2$X by applying random phase approximation...
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio
The macroscopic quantum tunneling (MQT) in the current biased high-Tc superconductor Josephson junctions and the effect of the zero energy bound states (ZES) on the MQT are theoretically...
Variational Monte Carlo studies of a t-J model on an anisotropic triangular lattice (2004)
Watanabe, Tsutomu, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro, Ogata, Masao
With the insulating phase of \kappa-(BEDT-TTF)_2X in mind, we study a t-J model on an anisotropic triangular lattice, where the hopping integral is t' in one of the three directions, using a...
Quasiparticle Dissipation in d-wave Superconductor Phase Qubit (2004)
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio
Recent phase sensitive experiments on high Tc superconductors, e.g., YBa_2Cu_3O_7 single crystals, have established the d-wave nature of the cuprate materials. Here we discuss how to make use of...
Variational Monte Carlo Studies of Pairing Symmetry for the t-J Model on a Triangular Lattice (2004)
Watanabe, Tsutomu, Yokoyama, Hisatoshi, Tanaka, Yukio, Inoue, Jun-ichiro, Ogata, Masao
As a model of a novel superconductor Na_xCoO_2\cdotyH_2O, a single-band t-J model on a triangular lattice is studied, using a variational Monte Carlo method. We calculate the energies of various...
Competition between singlet and triplet pairings in Na_xCoO_2 yH_2O (2004)
Kuroki, Kazuhiko, Tanaka, Yukio, Arita, Ryotaro
We discuss the pairing symmetry of a cobaltate superconductor Na$_x$CoO$_2\cdot y$ H$_2$O by adopting an effective single band model that takes into account the $e_g'$ hole pockets, as discussed in...
Kawabata, Shiro, Kashiwaya, Satoshi, Asano, Yasuhiro, Tanaka, Yukio
We examine the macroscopic quantum tunneling (MQT) in high-Tc superconductor Josephson junctions with a d-wave order parameter. Using microscopic Hamiltonian and the functional integral method, we...
Satomi Ikejima, Izumi Tsuneyama, Noriko Iida, Yuji Tsurui, Osamu Ninagi, Yukio Tanaka
The purpose of this study was to investigate the effects of calcium carbonate and saccharides on the feeding behavior of newly hatched larvae of the silkworm, Bombyx mori L. Japanese strains,...
Kuroki, Kazuhiko, Tanaka, Yukio, Arita, Ryotaro
We propose that spin-triplet pairing mechanism due to disconnected Fermi surfaces proposed in our previous study [Phys. Rev. B {\bf 63} 174507 (2001)] may be at work in a recently discovered...
Yokoyama, Hisatoshi, Tanaka, Yukio, Ogata, Masao, Tsuchiura, Hiroki
Superconductivity in the Hubbard model on a square lattice near half filling is studied using an optimization (or correlated) variational Monte Carlo method. Second-order processes of the...
Anomalous charge transport in mesoscopic triplet superconductor junctions (2003)
Tanaka, Yukio, Kashiwaya, Satoshi
Charge transport properties of a diffusive normal metal /triplet superconductor (DN/TS) junction are studied based on the Keldysh-Nambu quasiclassical Green's function formalism. % Contrary to the...
Quantum Monte Carlo study of the pairing symmetry competition in the Hubbard model (2003)
Kuroki, Kazuhiko, Tanaka, Yukio, Kimura, Takashi, Arita, Ryotaro
To shed light into the pairing mechanism of possible spin-triplet superconductors (TMTSF)$_2$X and Sr$_2$RuO$_4$, we study the competition among various spin singlet and triplet pairing channels in...
A phenomenological theory of zero-energy Andreev resonant states (2003)
Asano, Yasuhiro, Tanaka, Yukio, Kashiwaya, Satoshi
A conceptual consideration is given to a zero-energy state (ZES) at the surface of unconventional superconductors. The reflection coefficients in normal-metal / superconductor (NS) junctions are...
Nature of carriers in one-dimensional correlated electron systems (2003)
Tsuchiura, Hiroki, Ogata, Masao, Tanaka, Yukio, Kashiwaya, Satoshi
Electron densities at the edge site in one-dimensional Hubbard model and t-J model are studied by using the Bethe ansatz solutions and exact diagonalization method. It is found that the boundary is...
Electronic states around a vortex core in high-Tc superconductors based on the t-J model (2003)
Tsuchiura, Hiroki, Ogata, Masao, Tanaka, Yukio, Kashiwaya, Satoshi
Electronic states around vortex cores in high-Tc superconductors are studied using the two-dimensional t-J model in order to treat the d-wave superconductivity with short coherence length and the...
d_{x^2-y^2}- vs. d_{xy}- like pairings in organic superconductors \kappa-(BEDT-TTF)_2 X (2001)
Kuroki, Kazuhiko, Kimura, Takashi, Arita, Ryotaro, Tanaka, Yukio, Matsuda, Yuji
Pairing symmetry in $\kappa$-(BEDT-TTF)$_2$X is re-examined by applying fluctuation exchange method to the Hubbard model on the original four band lattice for the first time. Our study is motivated...
Theory of Spin polarized Tunneling in Superconducting Sr2RuO4 (1999)
Yoshida, Nobukatsu, Tanaka, Yukio, Inoue, Junichiro, Kashiwaya, Satoshi
A theory of tunneling conductance in ferromagnetic metal/insulator/triplet - supercondcutor junctions is presented for unitary and non-unitary spin triplet pairing states which are promising...
Tsuchiura, Hiroki, Tanaka, Yukio, Ogata, Masao, Kashiwaya, Satoshi
The local density of states (LDOS) around a magnetic impurity in high-Tc superconductors is studied using the two-dimensional t-J model with a realistic band structure. The order parameters are...
Intrinsic Josephson Effect in the Layered Two-dimensional t-J Model (1999)
Kawai, Noriaki, Tsuchiura, Hiroki, Tanaka, Yukio, Inoue, Jun-ichiro
The intrinsic Josephson effect in the high-Tc superconductors is studied using the layered two-dimensional t-J model. The d.c.Josephson current which flows perpendicular to the t-J planes is obtained...
Tsuchiura, Hiroki, Tanaka, Yukio, Ogata, Masao, Kashiwaya, Satoshi
The superconducting state around a well isolated nonmagnetic impurity in the high-Tc superconductors is studied using the two-dimensional t-J model. The spatial dependence of the order parameter and...
Tanaka, Yukio, Hirai, Takashi, Kusakabe, Koichi, Kashiwaya, Satoshi
We present a theory for the Josephson effect in an unconventional superconductor / one-dimensional electron gas / unconventional superconductor (s/o/s) junction, where the Josephson current is...
FRACTIONATION OF SERUM PROTEIN BY CM-CELLULOSE COLUMN, (1998)
Tanaka, Yukio, Iwashita, You, Nakakima, Yoshikazu, Kohi, Tsuyoshi, Noguchi, Sikazo
Employing CM-cellulose column, serum protein is eluted with pH 5.4 acetate buffer, and the composition of each fraction is identified by the paper electrophoresis of each fraction and the comparison...
Tanaka, Yukio, Kashiwaya, Satoshi
In order to examine the influences of the spatial dependence of the pair potential, the d.c. Josephson current in d-wave superconductors is calculated using self-consistently determined pair...
Theory of the d.c. Josephson effect in Pb / Sr2RuO4 / Pb (1998)
Yamashiro, Masashi, Tanaka, Yukio
To clarify the origin of anomalous behaviors in Pb/Sr2RuO4/Pb junctions in terms of the pairing symmetry, a theory of the d.c. Josephson current in s-wave superconductor / p-wave superconductor /...
Yamashiro, Masashi, Yoshida, Nobukatsu, Tanaka, Yukio, Kashiwaya, Satoshi
The properties of Josephson junction including a ferromagnetic insulating layer are studied theoretically. The calculated current shows the anomalous dependence on the magnitude of the exchange...
Theory of tunneling conductance for normal metal/insulator/triplet superconductor junctions (1997)
Yamashiro, Masashi, Tanaka, Yukio, Tanuma, Yasunari, Kashiwaya, Satoshi
Tunneling conductance spectra of normal metal/insulator/triplet superconductor junctions are investigated theoretically. As triplet paring states we select several types of symmetries that are...
Tunneling conductance of normal metal/insulator/Sr2RuO4 junction (1997)
Yamashiro, Masashi, Tanaka, Yukio, Kashiwaya, Satoshi
A theory of tunneling conductance spectra for normal metal/insulator/Sr$_{2}$RuO$_{4}$ junction is studied theoretically. We assume several types of pair potentials with triplet symmetries that are...