Strong spin depolarization in the ferromagnetic Weyl semimetal Co3Sn2 S2: Role of spin-orbit coupling

Abstract

Co3Sn2S2 has recently emerged as a ferromagnetic Weyl semimetal. Theoretical investigation of the spin-split bands predicted half metallicity in the compound. Here, we report the detection of a spin-polarized supercurrent through a Nb/Co3Sn2S2 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 very small spin polarization at different points with the degree of spin polarization ranging from 20% to 50% at the Fermi level of Co3Sn2S2. Our theoretical calculations of electronic density of states reveal a spin-depolarizing effect near the Fermi energy when the role of spin-orbit coupling is included. The inclusion of spin-orbit coupling also reveals particle-hole asymmetry that explains a large asymmetry observed in our experimental Andreev reflection spectra.