Spin-flip Raman scattering inn-type diluted magnetic semiconductors

Abstract

We report the results of a spin-flip Raman scattering study of electrons bound to shallow donors in the diluted magnetic semiconductors ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Te and ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$Se for x≲0.30 and in ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$ ${\mathrm{Mn}}_{\mathrm{x}}$S for x=0.022 and 0.125. Spin-flip Raman scattering is observed at temperatures ranging from 1.8 K to as high as 160 K and at magnetic fields ≤60 kG. The measured spin-flip energies are large and, for some samples, correspond to g values in excess of 100 at low temperatures. The enhancement of the Raman shifts results from the exchange coupling of the donor electron with the ${\mathrm{Mn}}^{2+}$ ions. The parameters of the mean-field approximation, used to describe the magnetic field and temperature dependence of g are shown to exhibit a temperature dependence for temperatures above 20 K. Finite Raman shifts are observed in the absence of a magnetic field and are attributed to the bound magnetic polaron and thermal fluctuations of the local magnetization. The temperature and magnetic field dependences of the spin-flip energies, Raman intensities, and polarizations were compared with the results of the statistical-mechanical model of Dietl and Spal/ek [Phys. Rev. B 28, 1548 (1983)]. The theory is in good agreement with the experimental results for x≲0.15.