Dynamic Jahn–Teller effect for an electronic E state coupled to the phonon continuum. II

Abstract

A coherent formalism describing the electron spin resonance of Jahn–Teller ions in 2E states in cubic crystals (the coupling being to the phonon continuum) is developed using thermal Green function techniques. The basic equation of the theory is a Wangsness–Bloch–Redfield equation of motion for the reduced density matrix for the combined spin and orbital degrees of freedom of the Jahn–Teller ion. The effective Hamiltonian and the t matrices describing phonon scattering processes are calculated by perturbation theory and several results for these quantities are given for both linear and quadratic orbit–lattice coupling. The effect of motional narrowing on the observed resonance spectrum of the 2E state is studied and results in agreement with experimental observations are found.