Zeeman spectrum of the1sexciton in very dilutedCd1−xCoxTecompounds

Abstract

A detailed study of the exciton Zeeman spectra in diluted magnetic semiconductor ${\mathrm{Cd}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{Te}(x<0.5%)$ is carried out at $T=1.6\mathrm{K}$ from magnetoreflection and magnetoabsorption in Faraday geometry. Analysis of ${\ensuremath{\sigma}}^{\ifmmode\pm\else\textpm\fi{}}$ reflectance spectra within the polariton model determines the transverse eigenenergies at different magnetic fields. The obtained energy pattern of the four Zeeman components shows unusual features which we explain by taking into account the longitudinal-transverse splitting and the electron-hole exchange interaction. Quantitative analysis of the energy spectrum carried out for various cobalt compositions yields the determination of the exchange constant ${N}_{0}\ensuremath{\beta}=\ensuremath{-}2.2\ifmmode\pm\else\textpm\fi{}0.15\mathrm{eV}.$ We also estimate the zero-field energy separation between $|1,M〉$ and $|2,M〉$ exciton states and the quadratic Zeeman shift.