Exciting odd-frequency equal-spin triplet correlations at metal-superconductor interfaces

Abstract

We predict the occurrence of odd-frequency equal-spin triplet correlations at normal metal-superconductor junction. This result is significant because equal-spin triplet correlations are associated with the presence of dissipation-less pure spin current. Inserting a spin-flipper at the interface of a normal metal-superconductor junction excites equal-spin triplet correlations. The existence of odd-frequency equal-spin triplet correlations in the absence of odd-frequency mixed-spin triplet correlations is the main conclusion of this work. It tallies well with the measured local magnetization density of states and spin-polarized local density of states at the interface. The importance of spin-flip scattering to the obtained results is manifest when we compare our normal metal-spin flipper-superconductor junction to other hybrid junctions where either only spin mixing or both spin mixing and spin-flip scattering are present.