Effects of Cr doping on the electronic structure of MnTe

초록

The effects of Cr doping on the electronic structure of semiconducting MnTe have been investigated by using electron and optical spectroscopies. All CrxMn1-xTe samples grown as polycrystalline films by molecular beam epitaxy oil Si(100) substrates showed a NiAs structure with little change in lattice parameters for x <= 0.15. X-ray photoelectron spectroscopy and spectroscopic ellipsometry results suggest the existence of spin-polarized Mn d bands in CrxMn1-xTe. The majority- and the minority-spin d bands are likely to be located similar to 4 eV below and similar to 3 eV above the Fermi level, respectively. The direct optical-band-gap of CrxMn1-xTe is found to gradually decrease with increasing x in the infrared region. A ferromagnetic behavior was observed for the CrxMn1-xTe films. The possible origin for the ferromagnetism is the coupling of Cr spins mediated by spin-polarized holes in the valence bands created through the hybridization between Te p and Cr d states.

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