Ultraviolet inverse-photoemission and photoemission spectroscopy studies of diluted magnetic semiconductors Cd1−x Mnx Te (0≤x≤0.7)

Electronic structures of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te films (0\ensuremath{\le}x\ensuremath{\le}0.7) grown epitaxially on GaAs(100) substrates have been investigated by means of in situ measurements of conduction-band inverse-photoemission and valence-band photoemission spectra. With increasing Mn concentration, the energy position of the conduction-band minimum shifts almost linearly toward higher energy relative to the valence-band maximum (VBM) as a result of an increasing contribution of the higher-lying Mn 4s level relative to the Cd 5s level. Features observed at 3.6 and -3.4 eV relative to the VBM are ascribed to emission from the Mn 3d\ensuremath{\downarrow} and 3d\ensuremath{\uparrow} states with ${\mathit{e}}_{\mathit{g}}$ symmetry, respectively, providing a spin-exchange splitting energy of 7.0\ifmmode\pm\else\textpm\fi{}0.2 eV. This value compares well with the predicted value in the theoretical investigation of electronic structures and magnetic properties of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$Te. Apart from one-electron band theory, the whole spectrum including multielectron satellites in the energy region between -5 and -9 eV is found to be in good agreement with that calculated in terms of the configuration-interaction theory using a ${\mathrm{Mn}}^{2+}$(${\mathrm{Te}}^{2\mathrm{\ensuremath{-}}}$${)}_{4}$ model cluster.