A new stress dilatometer and measurement of the thermal expansion under uniaxial stress of Mn$_3$Sn

TL;DR

This paper introduces a novel stress dilatometer to measure thermal expansion under uniaxial stress and applies it to Mn$_3$Sn, revealing how uniaxial compression affects its magnetic phase transition temperature and thermodynamic properties.

Contribution

The study presents a new measurement method for thermal expansion under tunable uniaxial stress and applies it to Mn$_3$Sn, providing insights into its magnetic phase transition behavior.

Findings

Uniaxial stress suppresses the transition temperature by 54.6 K at 1.51 GPa.

Thermal expansion anomaly occurs near 270 K, linked to magnetic structure change.

Entropy change at transition is approximately 0.1 J mol$^{-1}$ K$^{-1}$, weakly stress-dependent.

Abstract

We present a method for measuring thermal expansion under tunable uniaxial stresses, and show measurements of the thermal expansion of Mn$_3$Sn, a room temperature antiferromagnet that exhibits a spontaneous Hall effect, under uniaxial stresses of up to 1.51 GPa compression. Measurement of thermal expansion provides thermodynamic data about the nature of phase transitions, and uniaxial stress provides a powerful tuning method that does not introduce disorder. Mn$_3$Sn exhibits an anomaly in its thermal expansion near $\sim$270 K, associated with a first-order change in its magnetic structure. We show this transition temperature is suppressed by 54.6 K by 1.51 GPa compression along [0001]. We find the associated entropy change at the transition to be $\sim$ 0.1 J mol$^{-1}$ K$^{-1}$ and to vary only weakly with applied stress.