The study of electron dynamics in n-type CdS by spin-flip Raman scattering

Abstract

A review is presented of the application of spin-flip Raman scattering (SFRS) to the study of electron delocalization in the insulator–metal transition in n-type CdS. The delocalization in the metallic regime appears as a diffusional Dq ² term in the SFRS linewidth, where q is the light scattering vector, and D is well described for small q by the transport parameters of a non-interacting Fermi gas. The spin Faraday rotation, which is part of the same spin-photon interaction that gives rise to the SFRS, is used to measure selectively, the donor spin susceptibility, χ. Strong focus is placed on the properties of χ in the insulating region where the doped semiconductor is a model ‘amorphous antiferromagnet'. No evidence of any spin-glass-like ordering transition is found at temperatures even far below the percolation threshold. Pure spin diffusion without charge transport is also observed and gives information on spin correlations.