Phase-Sensitive Flux-Flow resistivity in Unconventional Superconductors

We theoretically investigate the magnetic-field-angle dependence of the flux-flow resistivity ρf in unconventional superconductors. Two contributions to ρf are considered: one is the quasiparticle (QP) relaxation time τ(kF) and the other is ω0(kF), which is a counterpart to the interlevel spacing of the QP bound states in the quasiclassical approach. Here, kF 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 ρf differs prominently between s-wave and d-wave pairs, reflecting the phase of the pair potentials. We also discuss the case where τ is constant and compare it with the more general case where τ depends on kF.