Revival of Strain Susceptibilities: Magnetostrictive Coefficient and Thermal-Expansion Coefficient

TL;DR

This paper emphasizes the importance of strain susceptibilities, specifically the magnetostrictive and thermal-expansion coefficients, as vital thermodynamic quantities that reveal quantum matter properties and phase transitions.

Contribution

It highlights recent advances in direct measurement techniques for strain susceptibilities and advocates for renewed focus on these fundamental thermodynamic properties.

Findings

Recent progress in measuring magnetostrictive coefficient dλ/dH

Advances in thermal-expansion coefficient dλ/dT measurement

Strain susceptibilities are fundamental and complementary to other thermodynamic properties

Abstract

In thermodynamics, volume is an essential extensive variable. Strain-line, area, or volume change-therefore offers a direct window into correlated quantum matter: tiny length changes {\Delta}L track how the lattice responds when state variables such as magnetic field H and/or temperature T are varied, revealing phases, transitions, and dynamics. Direct, high-precision strain measurements are already difficult; their susceptibilities are harder still. Very recently, several direct techniques have made vital progress on two key quantities: the magnetostrictive coefficient d{\lambda}/dH (often denoted qijk or dij in the magnetostriction literatures), and the linear thermal-expansion coefficient {\alpha}= d{\lambda}/dT. Considering these two strain susceptibilities together-they are fundamental and complementary-clarifies why these thermodynamic properties merit renewed attention.