Symmetric versus antisymmetric strain tuning of the valence transition in Yb(In$_{1-x}$Ag$_x$)Cu$_4$

TL;DR

This study investigates how symmetric and antisymmetric strain affect the valence transition in Yb(In$_{1-x}$Ag$_x$)Cu$_4$, revealing that volume-changing symmetric strains more effectively tune the transition than uniaxial strains.

Contribution

It demonstrates that symmetric (volume-changing) strains predominantly influence the valence transition, providing a quantitative understanding of stress effects on correlated quantum materials.

Findings

Hydrostatic stress more effectively tunes the transition than uniaxial stress.

Valence transition is mainly sensitive to symmetric strains and volume changes.

Results support the role of critical elasticity near the transition endpoint.

Abstract

Similar to transitions in a range of correlated quantum materials, the valence transition exhibits a strong coupling to the crystal lattice, rendering it highly sensitive to stress tuning. In the present work, we determine the effect of uniaxial stress, which breaks the lattice symmetry, on the valence transition temperature and its crossover temperature in pure and Ag-substituted YbInCu$_4$. Our key result is that hydrostatic stress is more effective in tuning this transition than uniaxial stress. Based on a symmetry decomposition of the stress-induced strains, we argue that this observation can be quantitatively understood, given that the valence transition is mostly sensitive to symmetric strains and thus volume changes of the lattice. These results support the notion that the valence transition can give rise to critical elasticity close to its critical endpoint.