Spin-orbit driven spin depolarization in the ferromagnetic Weyl semimetal Co3Sn2S2

TL;DR

This study investigates the spin polarization and depolarization mechanisms in the ferromagnetic Weyl semimetal Co3Sn2S2, revealing that spin-orbit coupling significantly reduces spin polarization near the Fermi level, contrary to prior predictions of half metallicity.

Contribution

The paper combines experimental Andreev reflection measurements with theoretical calculations to demonstrate spin depolarization effects caused by spin-orbit coupling in Co3Sn2S2.

Findings

Only 50% spin polarization at the Fermi level

Spin-orbit coupling induces spin depolarization

Particle-hole asymmetry explains spectral asymmetry

Abstract

Co$_3$Sn$_2$S$_2$ has recently emerged as a ferromagnetic Weyl semi-metal. Theoretical investigation of the spin-split bands predicted half metalicity in the compound. Here, we report the detection of a spin polarized supercurrent through a Nb/Co$_3$Sn$_2$S$_2$ point contact where Andreev reflection is seen to be large indicating a large deviation from half metallicity. In fact, analysis of the Andreev reflection spectra reveals only 50\% spin polarization at the Fermi level of Co$_3$Sn$_2$S$_2$. Our theoretical calculations of electronic Density of States (DOS) reveal a spin depolarizing effect near the Fermi energy when the role of spin-orbit coupling is included. Inclusion of spin-orbit coupling also reveals particle-hole asymmetry that explains a large asymmetry observed in our experimental Andreev reflection spectra.