Measurements of elastoresistance under pressure by combining in-situ tunable quasi-uniaxial stress with hydrostatic pressure

TL;DR

This paper introduces a novel experimental setup that combines in-situ tunable quasi-uniaxial stress with hydrostatic pressure to study electronic properties of materials, demonstrated through elastoresistance measurements on BaFe$_2$As$_2$.

Contribution

The work presents a new method to apply and control combined uniaxial and hydrostatic pressures in situ, enabling advanced studies of electronic phases in condensed matter physics.

Findings

Successful operation of the setup over 30K to 260K and up to 2GPa pressure.

Measurement of elastoresistance under combined pressures on BaFe$_2$As$_2$.

Discussion of implications for electronic nematicity research.

Abstract

Uniaxial stress, as well as hydrostatic pressure are often used to tune material properties in condensed matter physics. Here, we present a setup which allows for the study of the combined effects of quasi-uniaxial stress and hydrostatic pressure. Following earlier designs for measurements under finite stress at ambient pressure (e.g., Chu et al., Science 337, 710 (2012)), the present setup utilizes a piezoelectric actuator to change stress in situ inside the piston-cylinder pressure cell. We show that the actuator can be operated over the full temperature (from 30K up to 260 K) and pressure range (up to ~2GPa), resulting in a clear and measurable quasi-uniaxial strain. To demonstrate functionality, measurements of the elastoresistance (i.e., the change of resistance of a sample as a response to quasi-uniaxial strain) under finite hydrostatic pressure on the iron-based compound BaFe$_2$As$_2$ are presented as a proof-of-principle example, and discussed in the framework of electronic nematicity. Overall, this work introduces the combination of in situ tunable quasi-uniaxial stress and large (up to ~2GPa) hydrostatic pressure as a powerful combination in the study of novel electronic phases. In addition, it also points towards further technical advancements which can be made in the future.