Measurements of Elastic Properties of Langatate at Liquid Helium Temperatures for design of ultra low loss mechanical systems

TL;DR

This study characterizes the elastic properties of Langatate at liquid helium temperatures, providing essential data for designing ultra low loss mechanical systems used in precision frequency control and fundamental physics research.

Contribution

It offers the first comprehensive measurement of Langatate's elastic tensor coefficients at cryogenic temperatures, using a novel resonator-based method and Lagrangian formalism.

Findings

Determined temperature coefficients of Langatate's elastic tensor from 3.8K to 15K.

Identified power sensitivity and dominant loss mechanisms of LGT resonators at cryogenic temperatures.

Provided data crucial for designing low-loss mechanical systems in quantum and fundamental physics applications.

Abstract

We present full characterisation of acoustic wave devices based on the fully synthetic crystalline material at the liquid helium temperature range { required for the design of ultra low loss mechanical systems in many areas of research including frequency control and fundamental measurements}. Temperature coefficients of the effective elastic tensor of Langatate (LGT) in Lagrangian representation are determined for the temperature range $3.8-15$K. The Lagrangian formalism is mandatory in the analysed situation since the expansion coefficients of the LGT are still unknown at these temperatures. The measurement method involves a set of high-quality resonators of various cut angles, and uses measurements of frequency-temperature relations to extract the temperature coefficients of the elastic tensor. In addition, power sensitivity of LGT resonators at cryogenic temperatures is determined and dominant loss mechanism is identified.