Anomalous transport in normal-superconducting and ferromagnetic-superconducting nanostructures

Seviour, R. and Lambert, C. J. and Volkov, A. F. (1999) Anomalous transport in normal-superconducting and ferromagnetic-superconducting nanostructures. Physical review B, 59 (9). pp. 6031-6034. ISSN 0163-1829

Abstract

We have calculated the temperature dependence of the conductance variation [delta S(T)] of mesoscopic superconductor-normal-metal (S/N) structures, in the diffusive regime, analyzing both weak and strong proximity effects. We show that in the case of a weak proximity effect there are two peaks in the dependence of delta S(T) on temperature. One of them (known from previous studies) corresponds to a temperature T-1 of order of the Thouless energy (epsilon(Th)), and another, newly predicted maximum, occurs at a temperature T-2 where the energy gap in the superconductor Delta(T-2) is of order epsilon(Th). In the limit L-phi<L the temperature T-1 is determined by D (h) over bar/L-phi(2)(L-phi is the phase breaking length), and not epsilon(Th). We have also calculated the voltage dependence delta S(V) for a S/F structure (F is a ferromagnet) and predict nonmonotonic behavior at voltages of order the Zeeman splitting. [S0163-1829(99)04909-7].