Nonequilibrium effects in a Josephson junction coupled to a precessing spin

C. Holmqvist, S. Teber, M. Fogelström
2011 Physical Review B  
We present a theoretical study of a Josephson junction consisting of two s-wave superconducting leads coupled over a classical spin. When an external magnetic field is applied, the classical spin will precess with the Larmor frequency. This magnetically active interface results in a time-dependent boundary condition with different tunneling amplitudes for spin-up and spin-down quasiparticles and where the precession produces spin-flip scattering processes. We show that as a result, the Andreev
more » ... tates develop sidebands and a non-equilibrium population which depend on the precession frequency and the angle between the classical spin and the external magnetic field. The Andreev states lead to a steady-state Josephson current whose current-phase relation could be used for characterizing the precessing spin. In addition to the charge transport, a magnetization current is also generated.This spin current is time-dependent and its polarization axis rotates with the same precession frequency as the classical spin.
doi:10.1103/physrevb.83.104521 fatcat:3ciqdh2cybfs3md6squdoyysuy