We numerically study the electronic structure of a single vortex in two dimensional superconducting bilayer systems within the range of the mean-field theory. The lack of local inversion symmetry in the system is taken into account through the layer
dependent Rashba spin-orbit coupling. The spatial profiles of the pair potential and the local quasiparticle density of states are calculated in the clean spin-singlet superconductor on the basis of the quasiclassical theory. In particular, we discuss the characteristic core structure in the pair-density wave state, which is spatially modulated exotic superconducting phase in a high magnetic field.
We numerically study the effect of non-magnetic impurities on the vortex bound states in noncentrosymmetric systems. The local density of states (LDOS) around a vortex is calculated by means of the quasiclassical Greens function method. We find that
the zero energy peak of the LDOS splits off with increasing the impurity scattering rate.
We theoretically investigate the applied magnetic field-angle dependence of the flux-flow resistivity $rho_{rm f}(alpha_{rm M})$ for an uniaxially anisotropic Fermi surface. $rho_{rm f}$ is related to the quasiparticle scattering rate $varGamma$ insi
de a vortex core, which reflects the sign change in the superconducting pair potential. We find that $rho_{rm f}(alpha_{rm M})$ is sensitive to the sign-change in the pair potential and has its maximum when the magnetic field is parallel to the gap-node direction. We propose the measurement of the field-angle dependent oscillation of $rho_{rm f}(alpha_{rm M})$ as a phase-sensitive field-angle resolved experiment.
We numerically investigate the effect of in-plane anisotropic Fermi surface (FS) on the flux-flow resistivity $rho_{rm f}$ under rotating magnetic field on the basis of the quasiclassical Greens function method. We demonstrate that one can detect the
phase in pairing potential of Cooper pair through the field-angular dependence of $rho_{rm f}$ even if the FS has in-plane anisotropy. In addition, we point out one can detect the gap-node directions irrespective of the FS anisotropy by measuring $rho_{rm f}$ under rotating field.
We theoretically study the dependence of the quasiparticle (QP) scattering rate $varGamma$ on the uniaxial anisotropy of a Fermi surface with changing the magnetic field angle $alpha_{rm M}$. We consider the QP scattering due to the non-magnetic impu
rities inside a single vortex core. The field-angle dependence of the quasiparticle scattering rate $varGamma(alpha_{rm M})$ is sensitive to the sign-change of the pair potential. We show that with increasing the two dimensionality of the system, $varGamma(alpha_{rm M})$ reflects more clearly whether there is the sign-change in the pair potential.
We theoretically investigate the magnetic-field-angle dependence of the flux-flow resistivity $rho_{rm f}$ in unconventional superconductors. Two contributions to $rho_{rm f}$ are considered: one is the quasiparticle (QP) relaxation time $tau(bm{k}_{
rm F})$ and the other is $omega_0(bm{k}_{rm F})$, which is a counterpart to the interlevel spacing of the QP bound states in the quasiclassical approach. Here, $bm{k}_{rm F}$ denotes the position on a Fermi surface. Numerical calculations are conducted for a line-node s-wave and a d-wave pair potential with the same anisotropy of their amplitudes, but with a sign change only for a d-wave one. We show that the field-angle dependence of $rho_{rm f}$ differs prominently between s-wave and d-wave pairs, reflecting the phase of the pair potentials. We also discuss the case where $tau$ is constant and compare it with the more general case where $tau$ depends on $bm{k}_{rm F}$.
We theoretically investigate the quasiparticle scattering rate $varGamma$ inside a vortex core in the existence of non-magnetic impurities distributed randomly in a superconductor. We show that the dependence of $varGamma$ on the magnetic field direc
tion is sensitive to the sign of the pair potential. The behavior of $varGamma$ is quite different between an s-wave and a d-wave pair potential, where these are assumed to have the same amplitude anisotropy, but a sign change only for the d-wave one. It is suggested that measurements of the microwave surface impedance with changing applied-field directions would be used for the phase-sensitive identification of pairing symmetry.
