Spin-triplet current in half metal/conical helimagnet/superconductor heterojunctions

The BTK theory is extended to investigate spin-triplet current and differential conductance spectrum in the half metal/conical helimagnet (Holmium)/s-wave superconductor heterojunctions. We show that the effective spin-split and spin-flip scatterings of the Holmium layer control the conversion efficiency between the spin-singlet and equal-spin triplet pair correlations, leading to a tunneling current oscillation with the thickness of the Holmium layer. This can provide qualitative explanations on the current oscillation in Ho/Co/Ho-based Josephson junction experiment. The differential conductance spectrum confirms spin-flip Andreev reflection induced long-ranged equal-spin triplet pair correlations. (C) 2012 Elsevier B.V. All rights reserved.