Magneto-Elastic Coupling in a potential ferromagnetic 2D Atomic Crystal

TL;DR

This study demonstrates strong spin-phonon coupling in Cr2Ge2Te6, a promising 2D ferromagnetic semiconductor, revealing how lattice vibrations interact with magnetic order across a range of temperatures.

Contribution

First experimental evidence of spin-phonon coupling in Cr2Ge2Te6, a potential 2D atomic crystal, using high-resolution micro-Raman scattering.

Findings

Two low energy modes split in ferromagnetic phase

Phonon energies show an upturn below Tc

Phonon linewidths change dramatically below Tc

Abstract

Cr2Ge2Te6 has been of interest for decades, as it is one of only a few naturally forming ferromagnetic semiconductors. Recently, this material has been revisited due to its potential as a 2 dimensional semiconducting ferromagnet and a substrate to induce anomalous quantum Hall states in topological insulators. However, many relevant properties of Cr2Ge2Te6 still remain poorly understood, especially the spin-phonon coupling crucial to spintronic, multiferrioc, thermal conductivity, magnetic proximity and the establishment of long range order on the nanoscale. We explore the interplay between the lattice and magnetism through high resolution micro-Raman scattering measurements over the temperature range from 10 K to 325 K. Strong spin-phonon coupling effects are confirmed from multiple aspects: two low energy modes splits in the ferromagnetic phase, magnetic quasielastic scattering in paramagnetic phase, the phonon energies of three modes show clear upturn below Tc, and the phonon linewidths change dramatically below Tc as well. Our results provide the first demonstration of spin-phonon coupling in a potential 2 dimensional atomic crystal.