Nonvolatile Nematic Order Manipulated by Strain and Magnetic Field in a Layered Antiferromagnet

TL;DR

This study demonstrates that the layered antiferromagnet CoTa$_3$S$_6$ exhibits a switchable electronic nematic order that can be manipulated by strain and magnetic fields, revealing complex symmetry-breaking phenomena and potential for tunable functionalities.

Contribution

It reveals a controllable electronic nematic phase in CoTa$_3$S$_6$, showing how strain and magnetic fields can manipulate nematicity and uncovering its interplay with magnetic orders.

Findings

Nematic order evidenced by resistivity anisotropy and optical birefringence.

Nematicity can be manipulated by strain and magnetic field, with a non-volatile memory effect.

Broken three-fold symmetry can be restored by out-of-plane magnetic field.

Abstract

The operation mechanism of nematic liquid crystals lies in the control of their optical properties by the orientation of underlying nematic directors. In analogy, electronic nematicity refers to a state whose electronic properties spontaneously break rotation symmetries of the host crystalline lattice, leading to anisotropic electronic properties. In this work, we demonstrate that the layered antiferromagnet CoTa$_3$S$_6$ exhibits a switchable nematic order, evidenced by the emergence of both resistivity anisotropy and optical birefringence. This nematic state sets in at a temperature $T^*$ distinct from that of the antiferromagnetic transitions in the system, indicating a separate symmetry-breaking mechanism. The nematic order can be manipulated either by an in-plane rotation symmetry-breaking strain or in-plane magnetic field, with the latter exhibiting a pronounced non-volatile memory effect. Remarkably, we find that the broken three-fold rotation symmetry in electronic transport is restored with a moderate out-of-plane field. We hypothesize that the nematicity is of electronic origin and emerges from instabilities associated with van Hove singularities. The resulting phase diagram points to an intertwined interplay between the electronic nematicity and the proposed underlying collinear and non-coplanar spin orders. Our findings establish CoTa$_3$S$_6$ as a versatile antiferromagnetic platform with highly tunable functionalities arising from the breaking of rotational, time-reversal, and inversion symmetries.