A study of cooperative Jahn-Teller phase transitions in rare-earth vanadates by linear birefringence. II. DyVO4

Abstract

For pt.I see ibid., vol.10, p.2937 (1977). The authors have measured changes in linear birefringence ( Delta n) associated with the cooperative Jahn-Teller phase transition of DyVO₄ near 14K as a function of temperature and magnetic fields, B, between 0.024 and 0.095 T. Theoretical arguments show that Delta n is directly proportional to the order parameter of the transition and that B² is equivalent to the conjugate ordering field. By extrapolation to zero field they obtain the temperature dependence of the order parameter and the susceptibility. The data are compared with calculations based on a mean-field 'compressible' Ising model. For a reasonable choice of adjustable parameters this classical description gives a good fit to the data close to T_D consistent with general theoretical arguments and more detailed calculations, but it deviates progressively away from T_D presumably because of the known importance of short-range interactions in the system.