Millikelvin-compatible apparatus for studies of quantum materials under uniaxial stress

TL;DR

This paper presents a specialized apparatus capable of applying uniaxial stress to quantum materials at millikelvin temperatures, enabling detailed studies of strain-induced phenomena in quantum phase transitions.

Contribution

The authors introduce a novel millikelvin-compatible device for in situ uniaxial stress application with optical monitoring, facilitating advanced low-temperature quantum material research.

Findings

Successful characterization of superconducting strontium titanate under stress

Apparatus enables precise strain tuning at millikelvin temperatures

Provides a practical tool for ultra-low temperature uniaxial stress experiments

Abstract

Various new phenomena emerge in quantum materials under elastic deformations, such as hydrostatic or uniaxial stresses. In particular, using uniaxial strain or stress can help to tune or uncover specific structural or electronic orders in materials with multiple coexisting phases. Those phases may be associated with a quantum phase transition requiring a millikelvin environment combined with multiple experimental probes. Here, we describe our unique apparatus, which allows in situ tuning of strain in large samples inside a dilution refrigerator while the samples are monitored via an optical microscope. We describe the engineering details and show some typical results of characterizing superconducting strontium titanate under stress. This letter should serve as a practical reference for experts in ultra-low temperature experimental physics involving uniaxial stresses or strains.