Negative thermal expansion and magnetoelastic coupling in the breathing pyrochlore lattice material LiGaCr4S8

TL;DR

This study investigates LiGaCr4S8, revealing negative thermal expansion below 111 K and strong magnetoelastic coupling, with experimental and computational evidence linking magnetic and lattice properties.

Contribution

It provides the first detailed experimental and theoretical analysis of magnetoelastic effects and NTE in LiGaCr4S8, a breathing pyrochlore lattice material.

Findings

Negative thermal expansion below 111 K

Deviation from Curie-Weiss magnetic behavior

Strong lattice-magnetic coupling confirmed by calculations

Abstract

The physical properties of the spinel LiGaCr4S8 have been studied with neutron diffraction, X-ray diffraction, magnetic susceptibility and heat capacity measurements. The neutron diffraction and synchrotron X-ray diffraction data reveal negative thermal expansion (NTE) below 111(4) K. The magnetic susceptibility deviates from Curie-Weiss behavior with the onset of NTE. At low temperature a broad peak in the magnetic susceptibility at 10.3(3) K is accompanied by the return of normal thermal expansion. First principles calculations find a strong coupling between the lattice and the simulated magnetic ground state. These results indicate strong magnetoelastic coupling in LiGaCr4S8.