Zero Bias Conductance in d-Wave Superconductor/Ferromagnet/d-Wave Superconductor Trilayers

Abstract

Zero bias conductance (ZBC) in ballistic voltage-biased d-wave superconductor/ferromagnet/d-wave superconductor (DFD) junctions is studied theoretically, for various orientations of superconducting electrodes. We show that ZBC increases with exchange field h in the F barrier, up to some maximum value of h which is of the order of the pair potential in the superconducting electrodes. We find that for a given exchange field, ZBC monotonically decreases with temperature. When the exchange field h is smaller or of the order of the superconducting gap Δ, ZBC has a distinct kink at some characteristic temperature T*. It appears that for this temperature Δ(T*) = h. Thus, observing T* where the kink in the ZBC temperature dependence occurs provides a reliable measurement method to determine exchange fields of the order of the superconducting gap.