Electron-magnon scattering in an anisotropic half-metallic ferromagnetic Weyl semimetal Co3Sn2S2

Abstract

${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ is a magnetic Weyl semimetal, anisotropic ferromagnet, and half-metal in a single material. These qualities modify the spin dynamics and behavior of electron-magnon scattering. We have investigated this unconventional ferromagnet for modified electron-magnon scattering behavior using temperature and magnetic field dependent resistivity. ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ exhibits exponential suppression of spin-flip electron-magnon scattering below a characteristic crossover temperature which separates the regime of anomalous magnon scattering from one-magnon scattering. Interestingly, the Weyl fermion mediated spin dynamics with large magnetocrystalline anisotropy can also cause exponential suppression of electron-magnon scattering giving similar behavior in resistivity. The gap characterizing the suppression of electron-magnon scattering is 2.46(4) meV and increases linearly with magnetic field. The suppression of electron-magnon scattering could occur from half-metallic or anisotropic character but the presence of anomalous-magnon scattering at low temperatures evinces the half-metallic nature. A large anisotropy gap in magnon dispersion of half-metal can help prevent the deviation from 100% spin polarization at low temperatures.