Voltage-tunable spin supercurrent nonreciprocity reaching 100% efficiency

TL;DR

This paper demonstrates a superconductor/ferromagnet multilayer system that achieves electrically tunable, 100% efficient nonreciprocal spin supercurrent, enabling new functionalities in quantum technologies.

Contribution

It introduces a method to generate electrically tunable, nonreciprocal spin supercurrents with perfect efficiency in superconductor/ferromagnet multilayers, a novel advancement.

Findings

Nonreciprocal spin supercurrent reaches 100% efficiency.

Spin polarization of critical current is finite in one direction, zero in the opposite.

Underlying physics of the nonreciprocal phenomenon is explained.

Abstract

The superconducting version of a diode effect has been the subject of extensive research in the past few years. So far, the focus has almost exclusively been on charge transport, but a natural question is whether it is possible to obtain nonreciprocal spin transport without dissipation. Here, we demonstrate that it is possible to generate electrically tunable nonreciprocal spin transport carried by a supercurrent using superconductor/ferromagnet multilayers. The nonreciprocal spin supercurrent reaches an ideal efficiency of 100%, meaning that the spin-polarization of the critical current is finite in one flow direction whereas it vanishes in the other direction. We explain the underlying physics generating this phenomenon. This result provides a way to integrate nonreciprocal supercurrents with spin-polarization, offering new functionality in quantum technologies based on Josephson junctions.