Sub-gap conductance in ferromagnetic-superconducting mesoscopic structures
Abstract
We study the sub-gap conductance of a ferromagnetic mesoscopic region attached to a ferromagnetic and a superconducting electrode by means of tunnel junctions. In the absence of the exchange field, the ratio
r=γ/
ϵ
T
of the two tunnel junction resistances determines the behaviour of the sub-gap conductance which possesses a zero-bias peak for
r≫1
and for
r≪1
a peak at finite voltage. We show that the inclusion of the exchange field leads to a peak splitting for
r≪1
, while it shifts the zero-bias anomaly to finite voltages for
r≫1
.