Vibronic structure and g-tensor temperature dependence of K 2 ZnF 4 :Cu²⁺impurity center

Abstract

Adiabatic potential of K2ZnF4:Cu2 impurity system is calculated within the frames of pair potential approximation and shell model. The Jahn-Teller multi-body energy contribution is approximated by the lower branch of [CuF6] cluster adiabatic potential. It is shown that Qe-and Q-displacements ofthe distorted octahedron ofF ions surrounding Cu impurity ion may be assumed as the normal vibrational modes. Thus K2ZnF4:Cu2 vibronic states energy spectrum calculation reduces to the solution ofthe (Exe)-problem with the adiabatic potential, which contains not only the main terms (1/2.Ko'p2 H Vel P) but also relatively small corrections (-1/2.MC.p2cos(2p)+F.p'cosq) treated by perturbation theory. g-tensor components temperature dependences calculated by averaging over vibromc levels are consistent with the experimental data. Simulation of hydrostatic pressure influence on the K2ZnF4:Cu2 properties predicts essential changes in g-tensor components values and temperature dependences.