Gregory Czap, Kyungju Noh, et al.
APS Global Physics Summit 2025
Single crystal X-ray diffraction has been used to determine the magnitude and temperature dependence of the tetragonal-to-orthorhombic distortion below the cooperative Jahn-Teller phase transition occuring in TmVO4 at 2.15 K. The results are in good agreement with mean field theory and with the results of a previous investigation of the soft acoustic mode above the transition. It can be concluded that the interaction of long wavelength acoustic phonons with the ground doublet of the Tm3+ ion is the dominant mechanism for the transition. © 1974.