Giant elastocaloric effect at low temperatures in TmVO 4 and implications for cryogenic cooling

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Abstract
Adiabatic decompression of paraquadrupolar materials has significant potential as a cryogenic cooling technology. We focus on TmVO 4 , 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 k B ln 2 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 response of single-crystal TmVO 4 , 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 into the dynamic quadrupole strain susceptibility.
Funding Information
  • DOD | USAF | AMC | Air Force Office of Scientific Research (FA9550-20-1-0252)
  • NSF | National Science Foundation Graduate Research Fellowship Program (DGE-1656518)
  • Gordon and Betty Moore Foundation (GBMF9068)
  • National Science Foundation (DMR-2232515)
  • U.S. Department of Energy (DE-SC0020143)

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