Quantum-geometric spin and charge Josephson diode effects

Niklas L. Schulz; Danilo Nikolić; Matthias Eschrig

doi:10.1103/nb38-v1jq

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Quantum-geometric spin and charge Josephson diode effects

Niklas L. Schulz, Danilo Nikolić, Matthias Eschrig

DOI 10.1103/nb38-v1jq · Physical Review B

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Abstract

We present a general mechanism for large charge and spin Josephson diode effects in strongly spin-polarized superconductor-ferromagnet hybrid structures with a noncoplanar spin texture, formulated in terms of quantum-geometric phases. We present necessary conditions for this effect to occur, and show numerical results for disordered materials relevant to applications. We calculate Josephson diode efficiencies for both charge and spin diodes and show that a spin-diode efficiency of 100% can be reached. Finally, we present a SQUID device that can switch between nearly pure spin-up and spin-down equal-spin supercurrents across the ferromagnet by reversing the flux. These findings establish functionalities that are absent in coplanar spin textures.