Triplet superconductivity by the orbital Rashba effect at surfaces of elemental superconductors

Tom G. Saunderson; Martin Gradhand; Dongwook Go; James F. Annett; Maria Teresa Mercaldo; Mario Cuoco; Mathias Kläui; Jacob Gayles; Yuriy Mokrousov

arXiv · 2504.01271

Triplet superconductivity by the orbital Rashba effect at surfaces of elemental superconductors

Tom G. Saunderson·Martin Gradhand·Dongwook Go·James F. Annett·Maria Teresa Mercaldo·Mario Cuoco·Mathias Kläui·Jacob Gayles·Yuriy Mokrousov

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Abstract

It is often assumed that in a superconductor without spin-triplet pairing, the formation of unconventional spin-triplet densities requires the spin-orbit interaction in combination with either broken inversion symmetry or broken time-reversal symmetry. Here, we show from first principles the existence of supercurrent-driven spin triplet densities on the surface of a variety of simple superconducting materials without spin-orbit coupling. We are able to attribute this phenomenon to the superconducting non-relativistic orbital Rashba Edelstein effect. Furthermore, we find that the spin-orbit induced spin moment is one order of magnitude smaller than the orbital moment, and has a vanishing effect on the total magnitude of the induced triplet density. Our findings imply the existence of a route to generate spin-currents without the use of heavy metals. Additionally, as an orbital moment can couple directly to a magnetic field, it shows that orbital physics is the dominant term that drives the superconducting diode effect.

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Tom G. Saunderson, Martin Gradhand, Dongwook Go, James F. Annett, Maria Teresa Mercaldo, Mario Cuoco, Mathias Kläui, Jacob Gayles, Yuriy Mokrousov. 2025-04-02. Triplet superconductivity by the orbital Rashba effect at surfaces of elemental superconductors. https://arxiv.org/abs/2504.01271

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