Phase-Sensitive Impurity Effects in Vortex Core
of Moderately Clean Chiral Superconductors

Abstract

We study impurity effects in vortex core of two-dimensional moderately clean superconductors within the quasiclassical theory. The impurity scattering rate Γ(E) of the Andreev bound states in vortex core with +1 vorticity of p-wave superconductors with d=z(p_x+ip_y) is suppressed, compared to the normal state scattering rate Γ_n in the energy region Γ_n³/E_δ² << E << E_δ≡ |δ₀|Δ_∞ with scattering phase shift δ₀ (|δ₀| << 1) and the pair-potential in bulk Δ_∞. Further we find that Γ(E)/Γ_n for p-wave superconductors with d=z(p_x-ip_y) is at most O(E/Δ_∞). These results are in marked contrast to the even-parity case (s,d-wave), where Γ(E)/Γ_n is known to be proportional to ln(Δ_∞/E). Parity- and chirality-dependences of impurity effects are attributed to the Andreev reflections involved in the impurity-induced scattering between bound states. Implications for the flux flow conductivity is also discussed. Novel enhancement of flux flow conductivity is expected to occur at T << E_δ for d=z(p_x+ip_y) and at T << Δ_∞ for d=z(p_x-ip_y).