Effect of Applied Orthorhombic Lattice Distortion on the Antiferromagnetic Phase of CeAuSb$_2$

TL;DR

This study investigates how orthorhombic lattice distortions, induced by uniaxial pressure, influence the antiferromagnetic phase of CeAuSb$_2$, revealing symmetry-breaking effects and a transition from first-order to continuous phase transition.

Contribution

It demonstrates how uniaxial pressure along different lattice directions alters the magnetic order and transition nature in CeAuSb$_2$, highlighting the role of lattice symmetry in magnetic phase behavior.

Findings

First-order transition at zero pressure along $10$ direction.

Rotation of magnetic order axes from $10$ to $0$ with pressure.

Transition at $T_N$ changes from weakly first-order to continuous under $0$ pressure.

Abstract

We study the response of the antiferromagnetism of CeAuSb$_2$ to orthorhombic lattice distortion applied through in-plane uniaxial pressure. The response to pressure applied along a $\langle 110 \rangle$ lattice direction shows a first-order transition at zero pressure, which shows that the magnetic order lifts the $(110)/(1\bar{1}0)$ symmetry of the unstressed lattice. Sufficient $\langle 100 \rangle$ pressure appears to rotate the principal axes of the order from $\langle 110 \rangle$ to $\langle 100 \rangle$. At low $\langle 100 \rangle$ pressure, the transition at $T_N$ is weakly first-order, however it becomes continuous above a threshold $\langle 100 \rangle$ pressure. We discuss the possibility that this behavior is driven by order parameter fluctuations, with the restoration of a continuous transition a result of reducing the point-group symmetry of the lattice.