Evidence for anisotropic spin-triplet Andreev reflection at the 2D van der Waals ferromagnet/superconductor interface

TL;DR

This paper presents experimental evidence of anisotropic spin-triplet Andreev reflection at a 2D ferromagnet/superconductor interface, highlighting the role of Rashba spin-orbit coupling in inducing spin-triplet superconductivity.

Contribution

It reports the first observation of large magnetoresistance linked to spin-triplet Andreev reflection at a van der Waals ferromagnet/superconductor interface, advancing understanding of exotic superconducting states.

Findings

Large magnetoresistance observed at the interface.

Dependence of magnetoresistance on temperature, voltage, and barrier.

Evidence supporting induced spin-triplet superconductivity.

Abstract

Fundamental symmetry breaking and relativistic spin-orbit coupling give rise to fascinating phenomena in quantum materials. Of particular interest are the interfaces between ferromagnets and common s-wave superconductors, where the emergent spin-orbit fields support elusive spin-triplet superconductivity, crucial for superconducting spintronics and topologically-protected Majorana bound states. Here, we report the observation of large magnetoresistances at the interface between a quasi-two-dimensional van der Waals ferromagnet Fe0.29TaS2 and a conventional s-wave superconductor NbN, which provides the possible experimental evidence for the spin triplet Andreev reflection and induced spin-triplet superconductivity at ferromagnet/superconductor interface arising from Rashba spin-orbit coupling. The temperature, voltage, and interfacial barrier dependences of the magnetoresistance further support the induced spin-triplet superconductivity and spin-triplet Andreev reflection. This discovery, together with the impressive advances in two-dimensional van der Waals ferromagnets, opens an important opportunity to design and probe superconducting interfaces with exotic properties.