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

We study impurity effects in vortex core of two-dimensional moderately clean su perconductors within the quasiclassical theory. The impurity scattering rate $\G amma(E)$ of the Andreev bound states in vortex core with +1 vorticity of p-wav e superconductors with ${\mib d}=\hat{\mib z}(p_x+\iu p_y)$ is suppre ssed, compared to the normal state scattering rate $\Gamma_{\rm n}$ in the energ y region $\Gamma_{\rm n}^3/E_\delta^2\ll E\ll E_\delta\equiv |\delta_0|\Delta_\i nfty$ with scattering phase shift $\delta_0$ $(|\delta_0|\ll 1)$ and the pair-po tential in bulk $\Delta_\infty$. Further we find that $\Gamma(E)/\Gamma_{\rm n}$ for p-wave superconductors with ${\mib d}=\hat{\mib z}(p_x-\iu p_y)$ is at most ${\cal O}(E/\Delta_\i nfty)$. These results are in marked contrast to the even-parity case (s,d-wave), where $\Gamma(E)/\Gamma_{\rm n}$ is known to be proportional to $\ln(\Delta_\i nfty/E)$ . Parity- and chirality-dependences of impurity effects are attributed to the Andr eev reflections involved in the impurity-induced scattering between bound states . Implications for the flux flow conductivity is also discussed. Novel enhanceme nt of flux flow conductivity is expected to occur at $T\ll E_\delta$ for ${\mib d}=\hat{\mib z}(p_x+\iu p_y)$ and at $T\ll \Delta_\infty$ for ${\mib d}=\hat{\mib z}(p_x-\iu p_y)$.