Phase transitions and crossover at high magnetic fields in the Jahn-Teller compound DyVO4

The influence of a high magnetic field applied along the [001] axis on the magnetic properties of the Jahn-Teller compound DyVO4 is studied. Two phase transitions and a crossover effect are discovered. For T,TN=3 K the destruction of antiferromagnetic ordering of the magnetic moments of Dy 3+ ions along the [100] direction takes place at the fields around 12 T. In the neighborhood of 21 T the destruction of quadrupole ordering resulting in the change of the crystal symmetry occurs for all temperatures below the Jahn-Teller distortion temperature, T,TC=14 K. The orthorhombic-tetragonal phase diagram in the H–T plane is constructed. At higher fields the approaching of the low-lying energy levels of Dy3+ ions (crossover) exists in the tetragonal phase. These phase transitions and the crossover manifest themselves as pronounced anomalies of the differential magnetic susceptibility dM /dH, which is measured at the fields up to 36 T in the temperature range from 1.4 to 15 K. The effects under investigation are accounted for in the context of the unified approach, which is based on the crystal-field calculations and mean-field approximation.