Role of two-dimensional Ising superconductivity in the non-equilibrium quasiparticle spin-to-charge conversion efficiency

TL;DR

This study investigates how two-dimensional Ising superconductivity influences the efficiency of converting magnon spin to quasiparticle charge, revealing the importance of symmetry matching and spin-orbit fields for optimizing spin-to-charge conversion.

Contribution

It demonstrates the impact of out-of-plane spin-orbit fields on spin-to-charge conversion efficiency in 2D Ising superconductors, highlighting the role of symmetry matching in non-equilibrium conditions.

Findings

In-plane exchange spin-splitting is hindered by out-of-plane spin-orbit fields.

Symmetry matching between Cooper pairs and spin-splitting is crucial for efficient conversion.

Tuning exchange and spin-orbit fields can enhance spin-polarized triplet pairing.

Abstract

Non-equilibrium studies of two-dimensional (2D) superconductors (SCs) with Ising spin-orbit coupling are prerequisite for their successful application to equilibrium spin-triplet Cooper pairs and, potentially, Majorana fermions. By taking advantage of the recent discoveries of 2D SCs and their compatibility with any other materials, we fabricate here non-local magnon devices to examine how such 2D Ising superconductivity affects the conversion efficiency of magnon spin to quasiparticle charge in superconducting flakes of 2H-NbSe2 transferred onto ferrimagnetic insulating Y3Fe5O12. Comparison with a reference device based on a conventionally paired superconductor shows that the Y3Fe5O12-induced in-plane (IP) exchange spin-splitting in the NbSe2 flake is hindered by its inherent out-of-plane (OOP) spin-orbit-field, which, in turn, limits the transition-state enhancement of the spin-to-charge conversion efficiency. Our out-of-equilibrium study highlights the significance of symmetry matching between underlying Cooper pairs and exchange-induced spin-splitting for the giant transition-state spin-to-charge conversion and may have implications towards proximity-engineered spin-polarized triplet pairing via tuning the relative strength of IP exchange and OOP spin-orbit fields in ferromagnetic insulator/2D Ising SC bilayers.