Josephson current through a precessing spin

A study of the dc Josephson current between two superconducting leads in the presence of a precessing classical spin is presented. The precession gives rise to a time-dependent tunnel potential which not only creates different tunneling probabilities for spin-up and spin- down quasiparticles, but also introduces a time-dependent spin-flip term. In particular, we study the effects of the spin-flip term alone on the Josephson current between two spin-singlet superconductors as a function of precession frequency and junction transparency. The system displays a steady-state solution although the magnitude and nature of the current is indeed affected by the precession frequency of the classical spin