Elastoresistivity in the incommensurate charge density wave phase of BaNi$_{\textrm{2}}$(As$_{\textrm{1-x}}$P$_{\textrm{x}}$)$_{\textrm{2}}$

TL;DR

This study investigates the electronic nematicity in BaNi$_2$(As$_{1-x}$P$_x$)$_2$, revealing a strong elastoresistive response linked to incommensurate charge density waves and structural domain pinning, challenging previous models of nematic behavior.

Contribution

It demonstrates that elastoresistance in BaNi$_2$(As$_{1-x}$P$_x$)$_2$ is tied to incommensurate charge density waves, providing new insights into nematicity and structural distortions in this material.

Findings

Large $B_{1g}$ elastoresistance near the orthorhombic transition

Elastoresistance does not follow Curie-Weiss behavior

Hysteresis indicates pinning of orthorhombic domains

Abstract

Electronic nematicity, the breaking of the crystal lattice rotational symmetry by the electronic fluid, is a fascinating quantum state of matter. Recently, BaNi$_2$As$_2$ has emerged as a promising candidate for a novel type of nematicity triggered by charge fluctuations. In this work, we scrutinize the electronic nematicity of BaNi$_2$(As$_{1-x}$P$_x$)$_2$ with $0 \leq x \leq 0.10$ using electronic transport measurements under strain. We report a large $B_{1g}$ elastoresistance coefficient that is maximized at a temperature slightly higher than the first-order triclinic transition, and that corresponds to the recently discovered tetragonal-to-orthorhombic transition. The reported elastoresistance does not follow the typical Curie-Weiss form observed in iron-based superconductors but has a much sharper temperature dependence with a finite elastoresistance onsetting only together with a strong enhancement of the incommensurate charge density wave of the material. Consequently, the $B_{1g}$ elastoresistance and the associated orthorhombic distortion appears here as a property of this incommensurate charge density wave. Finally, we report and track the hysteretic behavior seen in the resistance versus strain sweeps and interpret its origin as the pinning of orthorhombic domains. Our results revise the understanding of the interplay between nematicity, charge density waves and structural distortions in this material.