Magnetization-control and transfer of spin-polarized Cooper pairs into a half-metal manganite

Anand Srivastava; Linde A. B. Olde Olthof; Angelo Di Bernardo; Sachio Komori; Mario Amado; Carla Palomares-Garcia; Mohammad Alidoust; Klaus Halterman; Mark G. Blamire; Jason W. A. Robinson

doi:10.1103/PhysRevApplied.8.044008

paper

Magnetization-control and transfer of spin-polarized Cooper pairs into a half-metal manganite

arXiv:1706.00332 · doi:10.1103/PhysRevApplied.8.044008

Abstract

The pairing state and critical temperature (T $_{c}$ ) of a thin s-wave superconductor (S) on two or more ferromagnets (F) are controllable through the magnetization-alignment of the F layers. Magnetization misalignment can lead to spin-polarized triplet pair creation, and since such triplets are compatible with spin-polarized materials they are able to pass deeply into the F layers and so, cause a decrease in T $_{c}$ . Various experiments on S/F $_{1}$ /F $_{2}$ "triplet spin-valves" have been performed with the most pronounced suppression of T $_{c}$ reported in devices containing the half-metal ferromagnet (HMF) CrO $_{2}$ (F $_{2}$ ) albeit using out-of-plane magnetic fields to tune magnetic non-collinearity [Singh et al., Phys. Rev. X 5, 021019 (2015)]. Routine transfer of spin-polarized triplets to HMFs is a major goal for superconducting spintronics so as to maximize triplet-state spin-polarization. However, CrO $_{2}$ is chemically unstable and out-of-plane fields are undesirable for superconductivity. Here, we demonstrate magnetization-tuneable pair conversion and transfer of spin-polarized triplet pairs to the chemically stable mixed valence manganite La $_{2/3}$ Ca $_{1/3}$ MnO $_{3}$ in a pseudo spin-valve device using in-plane magnetic fields. The results match microscopic theory and offer full control over the pairing state.

Magnetization-control and transfer of spin-polarized Cooper pairs into a half-metal manganite

Abstract

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