Phase-controlled proximity effect in ferromagnetic Josephson junctions: Calculation of the density of states and the electronic specific heat

Abstract

We study the thermodynamic properties of a dirty ferromagnetic S|F|S Josephson junction with s-wave superconducting leads in the low-temperature regime. We employ a full numerical solution with a set of realistic parameters and boundary conditions, considering both a uniform and nonuniform exchange field in the form of a Bloch domain wall. Our main result is that it is possible to strongly modify the electronic specific heat of the system by changing the phase difference between the two superconducting leads from zero up to nearly π. This is explained in terms of the proximity-altered density of state in the ferromagnetic region, and we discuss possible methods for experimental detection of the predicted effect.