Adiabatic decompression of para-quadrupolar materials has significant potential as a cryogenic cooling technology. We focus on TmVO4, an archetypal material that undergoes a continuous phase transition to a ferroquadrupole-ordered state at 2.15 K. Above the phase transition, each Tm ion contributes an entropy of kBln2 due to the degeneracy of the crystal electric field groundstate. Owing to the large magnetoelastic coupling, which is a prerequisite for a material to undergo a phase transition via the cooperative Jahn-Teller effect, this level splitting, and hence the entropy, can be readily tuned by externally-induced strain. Using a dynamic technique in which the strain is rapidly oscillated, we measure the adiabatic elastocaloric coefficient of single-crystal TmVO4, and thus experimentally obtain the entropy landscape as a function of strain and temperature. The measurement confirms the suitability of this class of materials for cryogenic cooling applications, and provides insight to the dynamic quadrupole strain susceptibility.
@article{arxiv.2308.15577,
title = {Giant elastocaloric effect at low temperatures in TmVO$_4$ and implications for cryogenic cooling},
author = {Mark P. Zic and Matthias S. Ikeda and Pierre Massat and Patrick M. Hollister and Linda Ye and Elliott W. Rosenberg and Joshua A. W. Straquadine and Brad J. Ramshaw and Ian R. Fisher},
journal= {arXiv preprint arXiv:2308.15577},
year = {2024}
}