Magnetostriction measurements at milli-kelvin temperatures using a Fabry-Pérot interferometer.

This paper demonstrates an optical technique to measure magnetostrictive strain in a cryogenic environment using a Fabry-Pérot resonator spaced by crystal samples. Optical measurement techniques are calibration-free and highly sensitive. This technique was used to measure the magnetostrictive strain of neodymium gallate at a temperature of 49 mK to be λ = 1.