Spin-density-wave order controlled by uniaxial stress in CeAuSb$_2$

TL;DR

This study demonstrates that uniaxial stress can induce a first-order transition in CeAuSb$_2$, changing its spin density wave order, which results in Fermi surface reconstruction and altered transport properties.

Contribution

It reveals that uniaxial stress can control SDW order and induce a new magnetic phase with a different propagation vector in CeAuSb$_2$, a heavy-fermion compound.

Findings

Uniaxial stress induces a first-order transition to a new SDW state with a different propagation vector.

The new magnetic structure involves alternating Ce layers with ordered and zero moments.

The transition correlates with changes in resistivity and Fermi surface topology.

Abstract

The tetragonal heavy-fermion compound CeAuSb$_2$ (space group $P4/nmm$) exhibits incommensurate spin density wave (SDW) order below $T_{N}\approx6.5~K$ with the propagation vector $\mathbf{q}_A = (\delta_A,\delta_A,1/2)$. The application of uniaxial stress along the [010] direction induces a sudden change in the resistivity ratio $\rho_a/\rho_b$ at a compressive strain of $\epsilon \approx -0.5$\%. Here we use neutron scattering to show that the uniaxial stress induces a first-order transition to a SDW state with a different propagation vector $(0,\delta_B,1/2)$ with $\delta_B=0.25$. The magnetic structure of the new (B) phase consists of Ce layers with ordered moments alternating with layers with zero moment stacked along the $c$-axis. The ordered layers have an up-up-down-down configuration along the $b$-axis. This is an unusual situation in which the loss of spatial inversion is driven by the magnetic order. We argue that the change in SDW wavevector leads to Fermi surface reconstruction and a concomitant change in the transport properties.