THE THEORY OF ESR HYPERFINE-STRUCTURE NARROWING AS APPLIED TO WIDE-GAP SEMIMAGNETIC SEMICONDUCTORS

The theory of ESR hyperfine-structure exchange narrowing is developed. The kinetic equations describing the nonequilibrium magnetization dyn amics of hyperfine components of ESR spectra are derived by using the nonequilibrium statistical-operator method. Numerical solution of thes e general equations is applied to the simulation of the experimental s pectra of (Cd, Mn)Te crystals with a Mn2+ ion content of between 0.05 and 0.5%, The hyperfine-splitting constant, homogeneous ESR linewidth, and mean-square value of the exchange fluctuation frequency are obtai ned from the fitting of the spectra for different concentrations of ma nganese ions. The concentration dependence of the latter quantity is d iscussed in relation to the spatial dependence of magnetic-ion exchang e interaction and the gap value in the band structure of semimagnetic semiconductors. (C) 1996 Academic Press, Inc.