arXiv subjects

K. Kawano

Publications and source records attributed to K. Kawano.

3 recordsLinked to original sources

arXiv2003

Mapping the Fermi velocity in the quasi-2D organic conductor k-(BEDT-TTF)2I3

We demonstrate a new method for determining the Fermi velocity in quasi-two-dimensional (Q2D) organic conductors. Application of a magnetic field parallel to the conducting layers results in periodic open orbit quasiparticle trajectories along the Q2D Fermi surface. Averaging of this motion over the Fermi surface leads to a resonance in the interlayer microwave conductivity. The resonance frequency is simply related to the extremal value of the Fermi velocity perpendicular to the applied field. Thus, angle dependent microwave studies enable a complete mapping of the Fermi velocity. We illustrate the applicability of this method for the highly-2D organic conductor k-(BEDT-TTF)2I3.

cond-mat.str-el↗

arXiv2001

Evidence for high inter-granular current flow in single-phase polycrystalline MgB2 superconductor

The distribution of magnetic field in single-phase polycrystalline bulk MgB2 has been measured using a Magneto-Optical (MO) technique for an external magnetic field applied perpendicular to the sample surface. The MO studies indicate that an inter-granular current network is readily established in this material and the current is not limited by weak-linked grain boundaries. The grain boundaries are observed to resist preferential magnetic field penetration, with the inter-grain mechanism dominating the current flow in the sample at temperatures up to 30K. The results provide clear evidence that the intra-granular current flow is isotropic. A critical current density of ~10^4 Acm-2 was estimated at 30K in a field of 150mT from the MO measurements. These results provide further evidence of the considerable potential for MgB2 for engineering applications.

cond-mat.supr-con↗

arXiv2000

Asymptotic expansion coefficients of the heat kernel in Riemann-Cartan space

By applying the covariant Taylor expansion method, the fifth lower coefficients the asymptotic expansion of the heat kernel associated with a fermion of spin 1/2 in Riemann-Cartan space are manifestly given. These coefficients in Riemann-Cartan space is derived from those obtained in Riemannian space by simple replacements.

hep-th↗