Quasiclassical theory of superconducting spin-splitter effects and spin-filtering via altermagnets

TL;DR

This paper develops a quasiclassical theory demonstrating how altermagnets enable controllable supercurrent-induced edge magnetization, spin-splitting, and filtering effects in superconductor-altermagnet hybrid devices, advancing superconducting spintronics.

Contribution

It introduces a theoretical framework for supercurrent-induced spin effects in altermagnets, revealing new functionalities for spin control in superconducting devices.

Findings

Edge magnetization controlled by supercurrent

Cooper pair spin-splitting and filtering effects predicted

Theoretical basis for experimental verification provided

Abstract

Conducting altermagnets have recently emerged as intriguing materials supporting strongly spin-polarized currents without magnetic stray fields. We demonstrate that altermagnets enable three key functionalities, merging superconductivity and spintronics. The first prediction is a controllable supercurrent-induced edge magnetization, which acts like a dissipationless spin-splitter effect. The second and third predictions are a Cooper pair spin-splitter and a filtering effect, respectively. These effects allow for spatial separation of triplet pairs with opposite spin-polarizations and spin-selective tunneling of Cooper pairs. We derive a quasiclassical theory with associated boundary conditions that describe these phenomena and explain how they can be experimentally verified. Our results open a new path for spatial control of spin signals via triplet Cooper pairs using hybrid superconductor-altermagnet devices.