http://publicationslist.org/data/nobuhiko.hayashi/atom.xml Nobuhiko Hayashihttp://publicationslist.org/nobuhiko.hayashi$basepathfavicon.icoRecent additions to Nobuhiko Hayashi's PublicationsList.org pagehttp://publicationslist.org/publications.png2011-05-25T08:24:01Z http://publicationslist.org/nobuhiko.hayashi/refid61 2011-01-24T03:37:36Z

Using the time-dependent Ginzburg-Landau equation with the complex relaxation time and the Maxwell equation, we systematically examine transverse motion of vortex dynamics in the presence of pinning disorders. Consequently, in the plastic flow phase in which moving and pinned vortices coexist, we find that the Hall voltage can generally change its sign. The origin of the sign change is ascribed to...<br/><br/>N. Nakai, N. Hayashi, and M. Machida (2011) <i>Phys. Rev. B</i> 83: 024507<br/>

http://publicationslist.org/nobuhiko.hayashi/refid63 2011-05-25T08:23:20Z

The contribution of the vortex core has been taken into account properly in constructing a torque theory for multiband superconductors. We employ the prescription for describing the internal magnetic field in the vortex lattice by Hao et al. and by Yaouanc et al. to derive a torque formula as a natural extension of a preceding London theory. In marked contrast with the preceding model, our formula...<br/><br/>D. Kubota, N. Hayashi, and T. Ishida (2011) <i>Phys. Rev. B</i> 83: 184518<br/>

http://publicationslist.org/nobuhiko.hayashi/refid56 2010-09-13T10:35:44Z

In order to consistently explain controversial experimental results on superconducting states observed by different probes in typical iron-based superconductors, we construct a realistic multiband s&plusmn;-wave pairing model by combining the quasiclassical formalism with the first-principles calculation. The model successfully resolves the controversies in contrast to the fact that simplified mod...<br/><br/>N. Nakai, H. Nakamura, Y. Ota, Y. Nagai, N. Hayashi, M. Machida (2010) <i>Phys. Rev. B</i> 82: 094501<br/>

http://publicationslist.org/nobuhiko.hayashi/refid57 2010-12-10T09:30:09Z

The inhomogeneous 3-Kelvin (3K) phase of the eutectic Sr2RuO4 with Ru inclusions nucleates superconductivity at the interface between Ru and Sr2RuO4. The structure of the interface state and its physical properties are examined here. Two superconducting phases are identified between the transitions to the bulk phase at 1.5 K and to the 3K phase. The nucleation of the 3K phase results in a state co...<br/><br/>H. Kaneyasu, N. Hayashi, B. Gut, K. Makoshi, and M. Sigrist (2010) <i>J. Phys. Soc. Jpn.</i> 79: 104705<br/>

http://publicationslist.org/nobuhiko.hayashi/refid58 2010-12-10T09:33:31Z

We briefly present three phenomenological theoretical works for superconducting properties in iron-based superconductors. The first is a suggestion of multi-band &plusmn;s-wave pairing model consistently explaining different measurement data, the second a proposal to detect &plusmn;s-wave signature, and the third an evaluation of the critical current in poly-crystalline samples by considering &plu...<br/><br/>M. Machida, Y. Nagai, Y. Ota, N. Nakai, H. Nakamura, and N. Hayashi (2010) <i>Physica C</i> 470: S372<br/>

http://publicationslist.org/nobuhiko.hayashi/refid62 2011-03-09T11:14:51Z

We demonstrate that a realistic multi-band model consistently explains the specific heat of typical iron-based superconductor. With density of states of each band obtained by first principle calculations, we evaluate multiple full-gap amplitudes from the angle resolved photoemission spectroscopy and successfully reproduce the specific heat. Consequently, it is found that the specific heat strongly...<br/><br/>N. Nakai, H. Nakamura, Y. Ota, Y. Nagai, N. Hayashi, and M. Machida (2010) <i>Physica C</i> 470: S368<br/>

http://publicationslist.org/nobuhiko.hayashi/refid60 2010-12-10T09:38:22Z

We theoretically discuss the magnetic-field-angle dependence of the zero-energy density of states (ZEDOS) in superconductors. Point-node and line-node superconducting gaps on spherical and cylindrical Fermi surfaces are considered. The Doppler-shift (DS) method and the Kramer–Pesch approximation (KPA) are used to calculate the ZEDOS. Numerical results show that consequences of the DS method are ...<br/><br/>N. Hayashi, Y. Nagai, and Y. Higashi (2010) <i>Physica C</i> 470: S865<br/>

http://publicationslist.org/nobuhiko.hayashi/refid59 2010-12-10T09:36:33Z

We discuss the surface Andreev bound states in Fe-based superconductors with the use of an effective five-band model and investigate the surface-angle dependence of the tunneling spectroscopy by a quasiclassical approach for an isotropic and an anisotropic &plusmn;s-wave gap superconductivity. We show that information on the normal state is important for the Andreev bound state and its peak positi...<br/><br/>Y. Nagai, N. Hayashi, and M. Machida (2010) <i>Physica C</i> 470: S504<br/>

http://publicationslist.org/nobuhiko.hayashi/refid50 2009-06-15T02:37:18Z

We discuss the tunneling spectroscopy at a surface in multi-band systems such as Fe-based superconductors with the use of the quasiclassical approach. We extend the single-band method by Matsumoto and Shiba [J. Phys. Soc. Jpn. 64, 1703 (1995)] into $n$-band systems ($n \geq 2$). We show that the appearance condition of the zero-bias conductance peak does not depend on details of the pair-potential...<br/><br/>Y. Nagai, N. Hayashi (2009) <i>Phys. Rev. B</i> 79: 224508<br/>

http://publicationslist.org/nobuhiko.hayashi/refid49 2009-03-24T15:51:14Z

The local density of states is studied theoretically in terms of the odd-frequency Cooper pairing induced around a vortex core. We find that a zero energy peak in the density of states at the vortex center is robust against nonmagnetic impurities in a chiral p-wave superconductor owing to an odd-frequency s-wave pair amplitude. We suggest how to discriminate a spin-triplet pairing symmetry and spa...<br/><br/>Y. Tanuma, N. Hayashi, Y. Tanaka, A. A. Golubov (2009) <i>PHYSICAL REVIEW LETTERS</i> 102: 117003<br/>

http://publicationslist.org/nobuhiko.hayashi/refid51 2009-08-10T05:56:46Z

In order to resolve a discrepancy of the magnetic moment on Fe between the experimental and calculation results, we perform first-principle electronic structure calculations for iron-based superconductors LaFeAsO1-xFx in which x=0.0 and x=0.125 by using the LSDA + U framework. Consequently, we confirm in both the mother and doped compounds that negative U correction is crucial in matching the calc...<br/><br/>H. Nakamura, N. Hayashi, N. Nakai, M. Okumura, M. Machida (2009) <i>Physica C</i> 469: 908-911<br/>

http://publicationslist.org/nobuhiko.hayashi/refid55 2009-08-10T06:03:40Z

We investigate the field-angle-dependent zero-energy density of states for YNi2B2C with using realistic Fermi surfaces obtained by band calculations. Both the 17th and 18th bands are taken into account. For calculating the oscillating density of states, we adopt the Kramer-Pesch approximation, which is found to improve accuracy in the oscillation amplitude. We show that superconducting gap structu...<br/><br/>Y. Nagai, N. Hayashi, Y. Kato, K. Yamauchi, H. Harima (2009) <i>J. Phys.: Conf. Ser.</i> 150: 052177<br/>

http://publicationslist.org/nobuhiko.hayashi/refid52 2009-08-10T05:58:31Z

In order to explore a superconducting mechanism on iron-based superconductors, we numerically study a two-band minimal model considering two degenerate d_xz and d_yz orbitals on Fe atom. We perform exact diagonalization on a two-band and two-leg square ladder totally composed of 10 lattice sites, which is computationally equivalent to 4-leg 20-sites square-Hubbard-ladder. Consequently, we find tha...<br/><br/>M. Okumura, N. Nakai, H. Nakamura, N. Hayashi, S. Yamada, M. Machida (2009) <i>Physica C</i> 469: 932-935<br/>

http://publicationslist.org/nobuhiko.hayashi/refid54 2009-08-10T06:01:46Z

We investigate the orientation of the vortex lattice driven by an applied current by means of numerical simulations based on the time-dependent Ginzburg–Landau (TDGL) theory. A lattice order is restored by a current driving of vortices under the influence of random vortex pinnings. The orientation of the moving vortex lattice is different between the presence and the absence of vortex pinnings. ...<br/><br/>N. Nakai, N. Hayashi, M. Machida (2009) <i>Physica C</i> 469: 1106-1109<br/>

http://publicationslist.org/nobuhiko.hayashi/refid53 2009-08-10T06:00:14Z

We perform first-principle phonon calculations for three typical iron-based superconductors, i.e., LaFeAsO,BaFe2As2, and FeSe. Though those crystals have different structures, we find that the optical modes associated with Fe vibration have almost similar characters. Moreover, we examine the pressure effect on phonons in FeSe. By increasing the external pressure, the phonon mode frequency related ...<br/><br/>H. Nakamura, N. Hayashi, N. Nakai, M. Machida (2009) <i>Physica C</i> 469: 1024-1026<br/>

http://publicationslist.org/nobuhiko.hayashi/refid1 2008-09-30T01:48:28Z

We study the Josephson effect between a conventional s-wave superconductor and a non-centrosymmetric superconductor with Rashba spin-orbit coupling. Rashba spin-orbit coupling affects the Josephson pair tunneling in a characteristic way. The Josephson coupling can be decomposed into two parts, a 'spin-singlet-like' and a 'spin-triplet-like' component. The latter component can lead to a shift of th...<br/><br/>N Hayashi, C Iniotakis, M Machida, M Sigrist (2008) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> <i></i> <i></i> 468: 7-10 844-847<br/>

http://publicationslist.org/nobuhiko.hayashi/refid44 2008-10-16T11:14:50Z

Superconductivity of nanosized Pb-island structures whose radius is 0.8 to 2.5 times their coherence length was studied under magnetic fields using low-temperature scanning tunneling microscopy and spectroscopy. Spatial profiles of superconductivity were obtained by conductance measurements at zero-bias voltage. Critical magnetic fields for vortex penetration and expulsion and for superconductivit...<br/><br/>T. Nishio, T. An, A. Nomura, K. Miyachi, T. Eguchi, H. Sakata, S. Lin, N. Hayashi, N. Nakai, M. Machida, Y. Hasegawa (2008) <i>PHYSICAL REVIEW LETTERS</i> 101: 167001<br/>

http://publicationslist.org/nobuhiko.hayashi/refid39 2008-09-30T02:19:07Z

Using the time-dependent Ginzburg-Landau equation with the complex relaxation rate and Maxwell equation, we perform the numerical simulation of vortex-pinning dynamics in two cases of metal-pinning and insulator-pinning. At the same time, the vortex-flow voltage induced by the vortex-motion and the Hall coefficient are calculated. Numerical simulations reveal that the trapped vortex at the pinning...<br/><br/>N. Nakai, N. Hayashi, M. Machida (2008) <i>PHYSICA C</i> 468: 1270-1273<br/>

http://publicationslist.org/nobuhiko.hayashi/refid40 2008-09-30T02:44:41Z

By measuring the angular-oscillations behavior of the heat capacity with respect to the applied field direction, one can detect the details of the gap structure. We introduce the Kramer-Pesch approximation as a new method to analyze the field-angle-dependent experiments, which improves the previous Doppler-shift technique. We show that the Fermi-surface anisotropy is an indispensable factor for id...<br/><br/>Yuki Nagai, Nobuhiko Hayashi (2008) <i>PHYSICAL REVIEW LETTERS</i> 101: 097001<br/>

http://publicationslist.org/nobuhiko.hayashi/refid45 2008-11-01T04:43:24Z

We discuss the nuclear magnetic relaxation rate and the superfluid density with the use of the effective five-band model by Kuroki et al (2008 Phys. Rev. Lett. 101 087004) in Fe-based superconductors. We show that a fully gapped anisotropic &plusmn;s-wave superconductivity consistently explains experimental observations. In our phenomenological model, the gaps are assumed to be anisotropic on the ...<br/><br/>Y. Nagai, N. Hayashi, N. Nakai, H. Nakamura, M. Okumura, M. Machida (2008) <i>NEW JOURNAL OF PHYSICS</i> 10: 103026<br/>

http://publicationslist.org/nobuhiko.hayashi/refid47 2008-12-06T05:13:17Z

We analyze the Josephson effect between a conventional and a non-centrosymmetric superconductor to examine characteristic features of such junctions and the symmetry of the superconducting phases. As a concrete example, we consider the non-centrosymmetric superconductor CePt3Si where Rashba spin–orbit coupling plays a crucial role and affects the Josephson pair tunneling. In this case, the Josep...<br/><br/>N. Hayashi, C. Iniotakis, M. Machida, and M. Sigrist (2008) <i>J. Phys. Chem. Solids</i> 69: 3225-3227<br/>

http://publicationslist.org/nobuhiko.hayashi/refid48 2008-12-06T05:15:29Z

By means of numerical simulations based on Ginzburg–Landau theory, we study the vortex depinning from a columnar defect in a superconducting film. We evaluate the limiting thickness of the film, below which the depinning does not occur even under an application of the magnetic field perpendicular to the columnar defect. The limiting thickness is a measure of the pinning strength of the columnar ...<br/><br/>N. Nakai, N. Hayashi, M. Machida (2008) <i>J. Phys. Chem. Solids</i> 69: 3301-3303<br/>

http://publicationslist.org/nobuhiko.hayashi/refid46 2008-11-27T16:08:23Z

We calculate the electronic structure for iron-based superconductors LaFeAsO1-xFx by using the LSDA+U framework. Consequently, we confirmed in the mother compound that the SDW and the orthorhombic structure becomes stable in a wide range of U. We show U dependence of the SDW magnetic moment and other properties. A highlight in this paper is that negative U correction is essential for matching the ...<br/><br/>H. Nakamura, N. Hayashi, N. Nakai, M. Machida (2008) <i>J. Phys. Soc. Jpn.</i> 77: Suppl. C 153-154<br/>

http://publicationslist.org/nobuhiko.hayashi/refid20 2008-10-02T08:44:22Z

To determine the superconducting gap function of YNi2B2C, we calculate the local density of states around a single vortex core with the use of Eilenberger theory and the band structure calculated by local density approximation, assuming various gap structures with point nodes at different positions. We also calculate the angular-dependent heat capacity in the vortex state on the basis of the Doppl...<br/><br/>Y Nagai, Y Kato, N Hayashi, K Yamauchi, H Harima (2007) <i>PHYSICAL REVIEW B</i> 76: 21 214514<br/>

http://publicationslist.org/nobuhiko.hayashi/refid4 2008-09-30T01:48:28Z

Superconductivity in non-centrosymmetric materials can display various intriguing properties. Using the example of the CePt3Si a phenomenological description of this non-centrosymmetric superconductor is given, in an attempt to identify the symmetry of the Cooper pairing state. A short overview on other recently discovered non-centrosymmetric superconductors mainly, in strongly correlated electron...<br/><br/>M Sigrist, D F Agterberg, P A Frigeri, N Hayashi, R P Kaur, A Koga, I Milat, K Wakabayashi, Y Yanase (2007) <i>JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS</i> <i></i> <i></i> 310: 2 536-540<br/>

http://publicationslist.org/nobuhiko.hayashi/refid3 2008-10-02T08:43:35Z

The tunneling characteristics of planar junctions between a normal metal and a noncentrosymmetric superconductor such as CePt3Si are examined. It is shown that the superconducting phase with mixed parity can give rise to characteristic zero-bias anomalies in certain junction directions. Andreev bound states at the interface are the origin of these zero-bias anomalies. The tunneling characteristics...<br/><br/>C Iniotakis, N Hayashi, Y Sawa, T Yokoyama, U May, Y Tanaka, M Sigrist (2007) <i>PHYSICAL REVIEW B</i> 76: 1 012501<br/>

http://publicationslist.org/nobuhiko.hayashi/refid2 2008-09-30T01:48:28Z

We study charge transport in normal metal/s+p-wave superconductor (S+P) junctions with Rashba type spin - orbit coupling (RSOC). Applying the Blonder - Tinkham - Klapwijk theory, we calculate a bias (V) dependence of tunneling conductance, changing the strength of RSOC and Delta(p)/Delta(s). Here Delta(s(p)) is the absolute value of pair potential of S(P) component. For Delta(p)<Delta(s), a gap st...<br/><br/>Y Sawa, T Yokoyama, Y Tanaka, C Iniotakis, N Hayashi, M Sigrist (2007) <i>PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES</i> <i></i> <i></i> 40: 2 281-284<br/>

http://publicationslist.org/nobuhiko.hayashi/refid38 2008-09-30T02:13:49Z

We briefly review the present status of our phenomenological study of superconductivity in non-centrosymmetric materials, with a strong focus on CePt3Si. The Anderson theorems are examined in the context of antisymmetric spin-orbit coupling. Then the behavior of superconductivity in high magnetic fields is discussed in particular in view of paramagnetic limiting and the presence of a so-called hel...<br/><br/>M. Sigrist, D. F. Agterberg, P. A. Frigeri, N. Hayashi, R. P. Kaur, A. Koga, I. Milat, K. Wakabayashi (2006) <i>AIP Conf. Proc.</i> 816: 124-135<br/>

http://publicationslist.org/nobuhiko.hayashi/refid21 2008-10-02T08:48:32Z

On the basis of the quasiclassical theory of superconductivity, we obtain a formula for the local density of states (LDOS) around a vortex core of superconductors with anisotropic pair-potential and Fermi surface in arbitrary directions of magnetic fields. Earlier results on the LDOS of d-wave superconductors and NbSe2 are naturally interpreted within our theory geometrically; the region with high...<br/><br/>Y Nagai, Y Ueno, Y Kato, N Hayashi (2006) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 75: 10 104701<br/>

http://publicationslist.org/nobuhiko.hayashi/refid22 2008-09-30T01:56:51Z

We numerically study the spatially resolved NMR around a single vortex in a noncentrosymmetric superconductor such as CePt3Si. The nuclear spin-lattice relaxation rate T-1(-1) under the influence of the vortex core states is calculated for an s + p-wave Cooper pairing state. The result is compared with that for an s-wave pairing state. (c) 2006 Elsevier B.V. All rights reserved.<br/><br/>N Hayashi, K Wakabayashi, P A Frigeri, Y Kato, M Sigrist (2006) <i>PHYSICA B-CONDENSED MATTER</i> <i></i> <i></i> 378-80: 388-390<br/>

http://publicationslist.org/nobuhiko.hayashi/refid7 2008-09-30T03:03:10Z

We numerically study the vortex core structure in a noncentrosymmetric superconductor such as CePt3Si without mirror symmetry about the xy plane. A single vortex along the z axis and a mixed singlet-triplet Cooper pairing model are considered. The spatial profiles of the pair potential, local density of states, supercurrent density, and radially-textured magnetic moment density around the vortex a...<br/><br/>N Hayashi, Y Kato, P A Frigeri, K Wakabayashi, M Sigrist (2006) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> 437-38: 96-99<br/>

http://publicationslist.org/nobuhiko.hayashi/refid23 2008-09-30T03:03:31Z

We numerically study the vortex core structure in a noncentrosymmetric superconductor such as CePt3Si without mirror symmetry about the xy plane. A single vortex along the z axis and a mixed singlet-triplet Cooper pairing model are considered. The spatial profiles of the pair potential, local density of states, supercurrent density, and radially-textured magnetic moment density around the vortex a...<br/><br/>N Hayashi, Y Kato, P A Frigeri, K Wakabayashi, M Sigrist (2006) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> 437-38: 96-99<br/>

http://publicationslist.org/nobuhiko.hayashi/refid8 2008-10-02T08:46:12Z

Noncentrosymmetric superconductors possess, in general, order parameters of mixed parity, i.e., the Cooper pairing state consists of spin-singlet and spin-triplet pairing components. We show that this property has important implications for the NMR and other measurable quantities in the heavy Fermion superconductor CePt3Si. The aspect of parity mixing explains the apparently contradicting observat...<br/><br/>N Hayashi, K Wakabayashi, P A Frigeri, M Sigrist (2006) <i>PHYSICAL REVIEW B</i> 73: 9 092508<br/>

http://publicationslist.org/nobuhiko.hayashi/refid9 2008-10-02T08:46:40Z

For a noncentrosymmetric superconductor such as CePt3Si, we consider a Cooper pairing model with a two-component order parameter composed of spin-singlet and spin-triplet pairing components. We calculate the superfluid density tensor in the clean limit on the basis of the quasiclassical theory of superconductivity. We demonstrate that such a pairing model accounts for an experimentally observed fe...<br/><br/>N Hayashi, K Wakabayashi, P A Frigeri, M Sigrist (2006) <i>PHYSICAL REVIEW B</i> 73: 2 024504<br/>

http://publicationslist.org/nobuhiko.hayashi/refid5 2008-10-02T08:44:49Z

We investigate the order parameter of noncentrosymmetric superconductors Li2Pd3B and Li2Pt3B via the behavior of the penetration depth lambda(T). The low-temperature penetration depth shows BCS-like behavior in Li2Pd3B, while in Li2Pt3B it follows a linear temperature dependence. We propose that broken inversion symmetry and the accompanying antisymmetric spin-orbit coupling, which admix spin-sing...<br/><br/>H Q Yuan, D F Agterberg, N Hayashi, P Badica, D Vandervelde, K Togano, M Sigrist, M B Salamon (2006) <i>PHYSICAL REVIEW LETTERS</i> 97: 1 017006<br/>

http://publicationslist.org/nobuhiko.hayashi/refid6 2008-09-30T01:48:28Z

We numerically study the spatially resolved NMR around a single vortex in a noncentrosymmetric superconductor such as CePt3Si. The nuclear spin-lattice relaxation rate T-1(-1) under the influence of the vortex core states is calculated for an s + p-wave Cooper pairing state. The result is compared with that for an s-wave pairing state. (c) 2006 Elsevier B.V. All rights reserved.<br/><br/>N Hayashi, K Wakabayashi, P A Frigeri, Y Kato, M Sigrist (2006) <i>PHYSICA B-CONDENSED MATTER</i> <i></i> <i></i> 378-80: 388-390<br/>

http://publicationslist.org/nobuhiko.hayashi/refid24 2008-10-02T08:48:02Z

We analytically study electronic bound states around a single vortex core in a noncentrosymmetric superconductor such as CePt3Si without mirror symmetry about the ab plane. Considering a mixed spin-singlet-triplet Cooper pairing model, we obtain a formula about the local density of states (LDOS) around a vortex core in any direction of the magnetic field. The LDOS under a magnetic field perpendicu...<br/><br/>Y Nagai, Y Kato, N Hayashi (2006) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 75: 4 043706<br/>

http://publicationslist.org/nobuhiko.hayashi/refid10 2008-09-30T01:48:28Z

The low-temperature shrinking of the vortex core (Kramer-Pesch effect) is studied for an isolated single vortex for chiral p-wave and s-wave superconducting phases. The effect of nonmagnetic impurities on the vortex core radius is numerically investigated in the Born limit by means of a quasiclassical approach. It is shown that in the chiral p-wave phase the Kramer-Pesch effect displays a certain ...<br/><br/>N Hayashi, Y Kato, M Sigrist (2005) <i>JOURNAL OF LOW TEMPERATURE PHYSICS</i> <i></i> <i></i> 139: 1-2 79-96<br/>

http://publicationslist.org/nobuhiko.hayashi/refid29 2008-09-30T03:00:44Z

We discuss the elementary vortex pinning in type-II superconductors in connection with the Anderson's theorem for nonmagnetic impurities. We address the following two issues. One is an enhancement of the vortex pinning energy in the unconventional superconductors. This enhancement comes from the pair-breaking effect of a nonmagnetic defect as the pinning center far away from the vortex core (i.e.,...<br/><br/>N Hayashi, Y Kato (2003) <i>JOURNAL OF LOW TEMPERATURE PHYSICS</i> 130: 3-4 193-206<br/>

http://publicationslist.org/nobuhiko.hayashi/refid35 2008-09-30T02:04:32Z

We study pseudo-gap temperature T* of high-T-c superconductors by a Monte Carlo simulation of anisotropic 3D Josephson junction array (JJA) model based on the Ginzburg-Landau theory. We investigate T* both in the cases of zero external current and finite external current I in the JJA. It is found that, the external current I depresses only a little the pseudo-gap temperature T*, while the supercon...<br/><br/>C Kawabata, M Takeuchi, N Hayashi, F Ono, S R Shenoy, A R Bishop (2003) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> <i></i> <i></i> 388: 31-32<br/>

http://publicationslist.org/nobuhiko.hayashi/refid28 2008-09-30T03:01:20Z

The vortex core in chiral p-wave superconductors exhibits various properties owing to the interplay between the vorticity and chirality inside the vortex core. In the chiral p-wave superconductors, the site-selective nuclear spin-lattice relaxation rate T-1(-1) is theoretically studied inside the vortex core within the framework of the quasiclassical theory of superconductivity. T-1(-1) at the vor...<br/><br/>N Hayashi, Y Kato (2003) <i>JOURNAL OF LOW TEMPERATURE PHYSICS</i> 131: 5-6 893-897<br/>

http://publicationslist.org/nobuhiko.hayashi/refid27 2008-09-30T01:56:51Z

We describe the essence of quantum effects inside s-wave and chiral p-wave vortices, without explicit use of quasiclassical Green function formalism. Physical quantities such as the impurity scattering rate and nuclear spin relaxation rate contain the coherence factor of the Andreev bound states in the matrix element of the transitions. The coherence factor of the Andreev bound state is different ...<br/><br/>Y Kato, N Hayashi (2003) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> <i></i> <i></i> 388: 519-520<br/>

http://publicationslist.org/nobuhiko.hayashi/refid26 2008-09-30T01:56:51Z

The site-selective nuclear spin-lattice relaxation rate T-1(-1) is theoretically studied inside a vortex core in a chiral p-wave superconductor within the framework of the quasiclassical theory of superconductivity. It is found that T-1(-1) at the vortex center depends on the sense of the chirality relative to the sense of the magnetic field. Our numerical result shows a characteristic difference ...<br/><br/>N Hayashi, Y Kato (2003) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> <i></i> <i></i> 388: 513-514<br/>

http://publicationslist.org/nobuhiko.hayashi/refid31 2008-09-30T01:58:55Z

The impurity problems within vortex cores of two-dimensional s-wave and chiral p-wave superconductors are studied numerically in the framework of the quasiclassical theory of superconductivity and self-consistent Born approximation under a trial form of the pair potential. The dispersion and impurity scattering rate (the inverse of the relaxation time) of the Andreev bound state localized in vorte...<br/><br/>Y Kato, N Hayashi (2002) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> <i></i> <i></i> 71: 7 1721-1727<br/>

http://publicationslist.org/nobuhiko.hayashi/refid36 2008-09-30T02:58:34Z

The boride compounds MBx related to the magnesium-boron stacking layered material MgB2 are discussed in terms of the B-B layers in the borides analogous to the Cu-O ones in the cuprates. We propose a possibility of superconducting materials which exhibit higher critical temperature T-c than 39 K of MgB2. We point out a role of interstitial ionic atoms M (e.g., Mg in MgB2) as capacitors, which redu...<br/><br/>C Kawabata, N Hayashi, F Ono (2002) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> 378: 220-224<br/>

http://publicationslist.org/nobuhiko.hayashi/refid32 2008-09-30T02:59:32Z

The elementary vortex pinning potential is studied in unconventional superconductors within the framework of the quasiclassical theory of superconductivity. Numerical results are presented for d-, anisotropic s-, and isotropic s-wave superconductors to show explicitly that in unconventional superconductors the vortex pinning potential is determined mainly by the loss of the condensation energy in ...<br/><br/>N Hayashi, Y Kato (2002) <i>PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS</i> 367: 1-4 41-45<br/>

http://publicationslist.org/nobuhiko.hayashi/refid30 2008-10-02T08:49:30Z

The elementary vortex pinning potential is studied in a chiral p-wave superconductor with a pairing d=(z) over bar((k) over bar (x)+/-i (k) over bar (y)) on the basis of the quasiclassical theory of superconductivity. An analytical investigation and numerical results are presented to show that the vortex pinning potential is dependent on whether the vorticity and chirality are parallel or antipara...<br/><br/>N Hayashi, Y Kato (2002) <i>PHYSICAL REVIEW B</i> 66: 13 132511<br/>

http://publicationslist.org/nobuhiko.hayashi/refid33 2008-09-30T02:57:03Z

The pair-potential and current, density around a single vortex of the two-dimensional chiral p-wave superconductor with d = (z) over cap (p(x) +/- ip(y)) are determined self-consistently within the quasiclassical theory of superconductivity. Shrinking of the vortex core at low temperatures are considered numerically and analytically. Temperature-dependences of the spatial variation of pair-potenti...<br/><br/>Y Kato, N Hayashi (2001) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 70: 11 3368-3376<br/>

http://publicationslist.org/nobuhiko.hayashi/refid37 2008-09-30T02:56:28Z

C Kawabata, N Hayashi, F Ono (2001) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 70: 10 3184-3185<br/>

http://publicationslist.org/nobuhiko.hayashi/refid34 2008-09-30T02:55:40Z

The most popular description of superconductivity phenomenon in Sr2RuO4r is based on a so-called single-band (usually gamma -band) "isotropic p-wave order parameter". In a magnetic field parallel to the conducting planes, such triplet "isotropic p-wave phase" is not destroyed by the Clogston-Chaldrasekhar paramagnetic limiting field and can be destroyed only by the Meissner currents (i.e., the orb...<br/><br/>A G Lebed, N Hayashi (2000) <i>PHYSICA C</i> 341: 1677-1678<br/>

http://publicationslist.org/nobuhiko.hayashi/refid42 2008-09-30T03:10:16Z

Electronic structure of a single vortex (or vortex core structure) in type-II superconductors is theoretically discussed in the present thesis. Low-lying excited states in the superconductors due to the vortex, i.e., "vortex bound states," are examined in detail on the basis of numerical calculations. Two points are focused on: the effect of superconducting gap anisotropy on a vortex and th...<br/><br/>Nobuhiko Hayashi (1999) <br/>

http://publicationslist.org/nobuhiko.hayashi/refid41 2008-09-30T02:54:49Z

The nondissipative transverse force acting an one moving vortex under the influence of another vortex is discussed in fermionic superfluid systems, where the relative velocity between the vortices is finite. On the basis of detailed numerical solutions of the Bogoliubov-de Gennes equation, the Berry phase for an adiabatic motion of the vortex line is examined for a two-vortex system. It is found t...<br/><br/>N Hayashi (1999) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 68: 10 3154-3157<br/>

http://publicationslist.org/nobuhiko.hayashi/refid43 2008-10-02T01:42:46Z

K. Machida, M. Ichioka, N. Hayashi, T. Isoshima (1998) <i>The Superconducting State in Magnetic Fields: Special Topics and New Trends</i> 245 - 271<br/>

http://publicationslist.org/nobuhiko.hayashi/refid12 2008-09-30T02:51:26Z

Focusing on a quantum-limit behavior, we study a single vortex in a clean s-wave type-II superconductor by self-consistently solving the Bogoliubov-de Gennes equation. The discrete energy levels of the vortex bound states in the quantum limit are discussed. The vortex core radius shrinks monotonically up to an atomic-scale length on lowering the temperature T, and the shrinkage stops to saturate a...<br/><br/>N Hayashi, T Isoshima, M Ichioka, K Machida (1998) <i>PHYSICAL REVIEW LETTERS</i> 80: 13 2921-2924<br/>

http://publicationslist.org/nobuhiko.hayashi/refid11 2008-09-30T02:52:00Z

Spatially inhomogeneous electron distribution around a single vortex is discussed on the basis of the Bogoliubov-de Gennes theory. The spatial structure and temperature dependence of the electron density around the vortex are presented. A relation between the vortex core charge and the vortex bound states (or the Caroli-de Gennes-Matricon states) is pointed out. Using the scanning tunneling micros...<br/><br/>N Hayashi, M Ichioka, K Machida (1998) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 67: 10 3368-3371<br/>

http://publicationslist.org/nobuhiko.hayashi/refid13 2008-09-30T02:50:50Z

An isolated single vortex is considered within the framework of the quasiclassical theory. The local density of states around a vortex is calculated in a clean type-II superconductor with an anisotropy. The anisotropy of a superconducting energy gap is crucial for bound states around a vortex. A characteristic structure of the local density of states, observed in the layered hexagonal superconduct...<br/><br/>N Hayashi, M Ichioka, K Machida (1997) <i>PHYSICAL REVIEW B</i> 56: 14 9052-9063<br/>

http://publicationslist.org/nobuhiko.hayashi/refid14 2008-09-30T02:50:13Z

The local density of states (LDOS) in the triangular vortex lattice is investigated based on quasiclassical Eilenberger theory. We consider the case of an isotropic s-wave superconductor with the material parameter appropriate to NbSe2. At a weak magnetic field, the spatial Variation of the LDOS shows a cylindrical structure around a vortex core. On the other hand, at a high field where the core r...<br/><br/>M Ichioka, N Hayashi, K Machida (1997) <i>PHYSICAL REVIEW B</i> 55: 10 6565-6576<br/>

http://publicationslist.org/nobuhiko.hayashi/refid17 2008-09-30T02:47:27Z

The vortex structure of pure d(x2-y2)-wave superconductors is microscopically analyzed in the framework of the quasiclassical Eilenberger equations. A self-consistent solution for the d-wave pair potential is obtained in the case of an isolated vortex. The vortex core structure, i.e., the pair potential, the supercurrent, and the magnetic field, is found to be fourfold symmetric even in the case t...<br/><br/>M Ichioka, N Hayashi, N Enomoto, K Machida (1996) <i>PHYSICAL REVIEW B</i> 53: 22 15316-15326<br/>

http://publicationslist.org/nobuhiko.hayashi/refid15 2008-09-30T02:49:03Z

The electronic structure of vortices in a type II superconductor is analyzed within the quasiclassical Eilenberger framework. The possible origin of a sixfold ''star'' shape of the local density of states, observed by scanning tunneling microscope (STM) experiments on NbSe2, is examined in the light of the three effects: the anisotropic pairing, the vortex lattice, and the anisotropic density of s...<br/><br/>N Hayashi, M Ichioka, K Machida (1996) <i>PHYSICAL REVIEW LETTERS</i> 77: 19 4074-4077<br/>

http://publicationslist.org/nobuhiko.hayashi/refid16 2008-09-30T02:48:19Z

The vortex core structure in a d-wave superconductor is analyzed by solving the quasi-classical Eilenberger equation self-consistently. The pair function, current and magnetic field distributions around an isolated vortex are found to break circular symmetry and show four-fold symmetry, reflecting the internal degrees of freedom in d-wave pairing.<br/><br/>K Machida, M Ichioka, N Hayashi, N Enomoto (1996) <i>PHYSICA C</i> 263: 1-4 428-430<br/>

http://publicationslist.org/nobuhiko.hayashi/refid18 2008-09-30T02:46:51Z

The vortex structure of d(x2-y2)-wave superconductors is microscopically analyzed in the framework of the quasiclassical Eilenberger equations. If the pairing interaction contains an s-wave (d(xy)-wave) component in addition to a d(x2-y2)-wave component, the s-wave (d(xy)-wave) component of the order parameter is necessarily induced around a vortex in d(x2-y2)-wave superconductors. The spatial dis...<br/><br/>M Ichioka, N Enomoto, N Hayashi, K Machida (1996) <i>PHYSICAL REVIEW B</i> 53: 5 2233-2236<br/>

http://publicationslist.org/nobuhiko.hayashi/refid19 2008-09-30T02:46:21Z

The vortex core structure in a d-wave superconductor is analyzed on the basis of the quasi-classical Eilenberger theory beyond the Ginzburg-Landau framework. The current and magnetic field distributions around an isolated vortex break the circular symmetry observed in s-wave pairing and show fourfold symmetry, reflecting, the internal degrees of freedom in d-wave pairing, i.e., (k) over cap(x)(2) ...<br/><br/>M Ichioka, N Hayashi, N Enomoto, K Machida (1995) <i>JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN</i> 64: 12 4547-4551<br/>