Field-modulated Nematic Fluctuation in CoTa3S6 Probed by Elastoresistance

Electronic nematicity refers to a state of matter in which rotational symmetry is spontaneously broken by electronic degrees of freedom. Initially observed in quantum Hall systems and later in high-temperature superconductors, nematicity has emerged as a ubiquitous ingredient in correlated electron physics. Recently, the layered antiferromagnet CoTa3S6 has been found to host a non-volatile nematic order that can be switched by in-plane strain or magnetic field [1]. To resolve the nature of the intertwined nematic phase and non-coplanar magnetic order, we investigate nematic fluctuations in CoTa3S6 using elastoresistance measurements and map out the phase diagram as a function of out-of-plane magnetic field. Our results reveal a susceptibility-like elastoresistance with strong magnetic field modulation, implying that elastoresistance is a sensitive probe of the interplay between magnetic field and rotation symmetry breaking. Along with free energy model analysis, we show compelling evidence that the nematic order arises from a degree of freedom distinct from the underlying antiferromagnetic order.