Highly anisotropic strain dependencies in PrIr$_2$Zn$_{20}$

TL;DR

This study investigates the highly anisotropic strain responses in PrIr₂Zn₂₀, revealing minimal volume change across magnetic phases, suggesting stable Pr valence and c-f hybridization, contrasting with Kramers Kondo lattices.

Contribution

It provides the first detailed measurement of anisotropic thermal expansion and magnetostriction in PrIr₂Zn₂₀, highlighting the minimal volume strain and stable valence state across magnetic phases.

Findings

Volume strain is very small, indicating stable Pr valence.

Thermal expansion and magnetostriction are highly anisotropic.

Fermi liquid state forms with minimal change in c-f hybridization.

Abstract

We report thermal expansion and magnetostriction of the cubic non-Kramers system PrIr$_2$Zn$_{20}$ with a non-magnetic $\varGamma_{3}$ ground state doublet. In previous experiments, antiferroquadrupolar order at \hbox{$T_{\mathrm{Q}}=0.11$\,K} and a Fermi liquid state around $B_{\mathrm{c}}\approx5$\,T for \hbox{$\boldsymbol{B}\parallel[001]$}, indicative of possible ferrohastatic order, were discovered. For magnetic fields \hbox{$\boldsymbol{B}\parallel[001]$}, the low temperature longitudinal and transverse thermal expansion and magnetostriction are highly anisotropic. The resulting volume strain is very small, indicating that the Pr valence remains nearly constant as a function of magnetic field. We conclude that the Fermi liquid state around $B_{\mathrm{c}}$ forms through a very little change in c-f hybridization. This result is in sharp contrast to Ce- and Yb-based Kramers Kondo lattices which show significantly larger volume strains due to the high sensitivity of the Kondo temperature to hydrostatic pressure.