Induced Jahn-Teller transition in DyPO4 caused by a change in ground stateupon level crossing

The transition caused by a change in the ground state of a rare-earth ion u pon level crossing, an analogue of the induced Jahn-Teller transition in ra re-earth compounds, is observed. It is shown that a jumpwise change in the Jahn-Teller interactions of alpha and gamma symmetries, caused by a change in the corresponding quadrupole moments in DyPO4 upon level crossing, dimin ishes the critical field by similar to 20 kOe and leads to a sharper change in magnetization M and differential magnetic susceptibility dM/dH near the crossover point. (C) 2001 MAIK "Nauka/Interperiodica".