Piezomagnetic effect in 5$d$ transition metal oxides Y$_2$Ir$_2$O$_7$ and Cd$_2$Os$_2$O$_7$ with all-in/all-out magnetic order

TL;DR

This study demonstrates the presence of a piezomagnetic effect in pyrochlore oxides Y$_2$Ir$_2$O$_7$ and Cd$_2$Os$_2$O$_7$, linking magnetic multipole order to stress-induced magnetization, and estimates the piezomagnetic tensor for both materials.

Contribution

It provides the first quantitative estimation of the piezomagnetic tensor in these pyrochlore oxides and discusses the microscopic mechanisms involving magnetic multipoles.

Findings

Linear magnetization development under stress in both materials.

Estimated piezomagnetic tensor values at 50 K.

Discussion of stress effects on g-tensor and Dzyaloshinskii-Moriya interactions.

Abstract

We investigated the piezomagnetic effect in pyrochlore-type oxides Y$_2$Ir$_2$O$_7$ and Cd$_2$Os$_2$O$_7$, which show a non-coplanar magnetic structure called the all-in/all-out antiferromagnetic order at low temperatures. The all-in/all-out magnetic order can be viewed as a ferroic order of the $xyz$-type magnetic octupoles. We observed a linear development of magnetization with applying stress for both materials. We then estimated the powder-averaged piezomagnetic tensor at 50 K to be $Q = 5.74 \times 10^{-6}$ $\mu_{\text{B}}$/Ir$\cdot$MPa for Y$_2$Ir$_2$O$_7$, and $Q = 3.49 \times 10^{-7}$ $\mu_{\text{B}}$/Os$\cdot$MPa for Cd$_2$Os$_2$O$_7$. We discuss the microscopic mechanism of the piezomagnetic effect in terms of the stress-induced modification of the g-tensor anisotropy and Dzyaloshinskii-Moriya (D-M) interactions. This work paves the way for the further development of piezomagnetic materials using a strategy based on magnetic multipoles.