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Solid-State Laser Refrigeration at GPa Pressures

submitted on 16.06.2020 and posted on 26.06.2020 by Abbie S. Ganas, Elena Dobretsova, Anupum Pant, Baptiste Journaux, Xiaojing Xia, Robert G. Felsted, Peter Pauzauskie
Although solid-state laser-refrigeration recently has been demonstrated to reach cryogenic temperatures in vacuum, to date the solid-state laser refrigeration of materials at elevated pressure conditions has remained unexplored. Here we demonstrate the laser cooling of ytterbium-doped yttirum-lithium-fluoride (10%Yb3+:YLiF4, or Yb:YLF)
>17K below room temperature at pressures >4 GPa in a diamond anvil cell using lithium fluoride and ice-VII as a quasi-hydrostatic pressure media. Temperature measurements are quantified using a ratiometric-thermometry approach involving a Boltzmann fit to excited states distribution through 4f-4f Stark-level transitions from the Yb3+ ions that occur between the 2F5/2 and 2F7/2 manifolds. At pressures between 7 and 12 GPa the YLF grains are observed to undergo a martensitic phase transition from a tetragonal scheelite phase (space group I41/a, Z = 4, No. 88) to a monoclinic fergusonite phase (space group I2/a, Z = 4, No. 15) which modifies the crys-
tal field splitting of the ground- and excited- state manifolds, but is observed to not eliminate laser cooling. Solid-state laser refrigeration at extreme pressures could allow researchers to use rapid photothermal cycling to explore temperature-dependent properties of materials, including electronic-structure phase-transitions, without the need for external cryostats.


Email Address of Submitting Author


University of Washington, Seattle


United States

ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest

Version Notes

Re-uploaded mainmanuscript and SI