Thermal Expansion and Volume Magnetostriction in Breathing Pyrochlore Magnets LiACr$_4$X$_8$ (A = Ga, In, X = O, S)

TL;DR

This study investigates thermal expansion and magnetostriction in breathing pyrochlore magnets LiACr4X8, revealing complex volume and magnetic behaviors linked to their structure, with potential for novel volumetric magnetic phenomena.

Contribution

It provides the first detailed measurements of thermal and magnetostrictive properties in these specific breathing pyrochlore compounds, highlighting their complex magneto-structural correlations.

Findings

Large volume contraction with antiferromagnetic order

Negative thermal expansion in LiGaCr4S8

Positive forced volume magnetostriction in LiInCr4S8

Abstract

We report thermal expansion and magnetostriction in breathing pyrochlore magnets LiACr$_4$X$_8$ (A = Ga, In, X = O, S) measured by a dilatometric method on sintered samples. All four of these compounds showed a large volume contraction associated with antiferromagnetic order with decreasing temperature. Above the Ne\'el temperature, LiGaCr4S8 showed negative thermal expansion, LiInCr4O8 showed positive thermal expansion with concave-downward temperature dependence, and LiInCr4S8 showed positive forced volume magnetostriction. All these phenomena are likely caused by the complex structure-magnetism correlation within the breathing pyrochlore structure with J and J'. These results suggested that breathing pyrochlore magnets are promising for the realization of various volumetric phenomena related to their magnetism not only in the magnetically-ordered phase but also in the paramagnetic phase.