Interband Faraday effect in Cd1-xMnxSe.

Abstract

The interband Faraday rotation in the uniaxial diluted magnetic semiconductor ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Se, measured with the direction of propagation k^ and the magnetic field H along its optic axis (c^), has been investigated for 0\ensuremath{\le}x<0.5. The Faraday rotation, positive for CdSe, becomes negative and very large when ${\mathrm{Mn}}^{2+}$ replaces ${\mathrm{Cd}}^{2+}$. The sign of the rotation and its dependence on x, H, and temperature T are dominated by the spin-spin exchange interaction between the spins of the 3d electrons of ${\mathrm{Mn}}^{2+}$ and those of the band electrons. The dispersion of the Verdet constant is well described by the excitonic model (single-oscillator model). The antiferromagnetic coupling between ${\mathrm{Mn}}^{2+}$ ions is manifested in the Faraday effect through the phenomenological effective temperature (T+${T}_{\mathrm{AF}}$), as well as with hysteresis effects associated with the formation of a spin-glass phase for high x and low T.