Strong effects of uniaxial pressure and short-range correlations in Cr2Ge2Te6

TL;DR

This study demonstrates that uniaxial pressure significantly influences the magnetic transition temperature in Cr2Ge2Te6, revealing strong magnetoelastic coupling and short-range magnetic correlations up to 200 K, with implications for engineering room-temperature ferromagnetism.

Contribution

The paper provides quantitative evidence of large uniaxial pressure effects and magnetoelastic coupling in Cr2Ge2Te6, highlighting the potential to enhance ferromagnetism via strain engineering.

Findings

Uniaxial pressure greatly affects the Curie temperature.

Strong magnetoelastic coupling is observed.

Short-range magnetic order persists up to 200 K.

Abstract

Cr$_2$Ge$_2$Te$_6$ is a quasi-2D semiconducting van der Waals ferromagnet down to the bilayer with great potential for technological applications. Engineering the critical temperature to achieve room temperature applications is one of the critical next steps on this path. Here, we report high-resolution capacitance dilatometry studies on Cr$_2$Ge$_2$Te$_6$ single crystals which directly prove significant magnetoelastic coupling and provide quantitative values of the large uniaxial pressure effects on long-range magnetic order (${\partial}T_{\mathrm{C}}/{\partial}p_{\mathrm{c}}$ = 24.7 K/GPa and ${\partial}T_{\mathrm{C}}/{\partial}p_{\mathrm{ab}}$ = $-$15.6 K/GPa) derived from thermodynamic relations. Moderate in-plane strain is thus sufficient to strongly enhance ferromagnetism in Cr$_2$Ge$_2$Te$_6$ up to room temperature. Moreover, unambiguous signs for short-range magnetic order up to 200~K are found.