REENTRANT STRUCTURAL PHASE-TRANSITIONS INDUCED BY EXTERNAL MAGNETIC-FIELDS IN TMXLU1-XPO4 AND TBXY1-XVO4 CRYSTALS

In the framework of microscopic theory of structural phase transitions on the basis of the cooperative Jahn-Teller effect, the phase diagrams of the TmxLu1-xPO4 and TbxY1-xVO4 crystals under external magnetic fields are calculated. It is shown that depending upon the concentration of the Jahn-Teller ions and the value of the magnetic field one, two, or none of the phase transitions take place. The results are in agreement with the earlier suggested theory of the stimulated cooperative Jahn-Teller effect and the experimental data on the giant magnetostriction and Raman scattering. © 1995 The American Physical Society.