Theory of Spin Disorder Scattering in Heavily Mn-Doped GaAs: A Self-Consistent Approach

Abstract

We have studied the theory of spin disorder scattering in Mn-doped GaAs by calculating in the weak coupling limit the charge carrier mobility limited by the critical scattering. The theory is developed by using Matsubara's temperature Green's functions and treating the exchange interaction between the carrier spins and the localized magnetic moments of the Mn-ions as a perturbation. The carrier life-time and the perturbed band energy are both calculated from the second order self-energy in a self-consistent manner in the sense that first the infinite order correction to the band energy is calculated by iterations, and then the corrected energy is inserted in the expression for the carrier life-time. Adding a contribution from the impurity scattering the total hole mobility can be estimated. Comparison of the calculated results to the experimental magnetotransport data shows good agreement. However, the measured resistivity peak near the Curie temperature is broader than the calculated one, which together with the large exchange parameter calls for an extension of the present theory to the intermediate or strong coupling cases.