The Optical Properties of MnAs and MnAs(0.85)P(0.15).

摘要

The reflectivity spectra of MnAs (hexagonal NiAs structure) and MnAs(0.85)P(0.15) (orthorhombic lattice) are measured in the energy range 0.3 to 14 eV at room temperature and a Kramers-Kronig analysis is performed. It is found that below 1 eV plasma effects due to free d-electrons dominate. At energies from 3 to 8 eV plasma resonances due to bound d-electrons are observed. In the intermediate region, the imaginary part of the dielectric constant epsilon sub 2 reveals structure due to transitions between d-states and from the valence band into d- and sp states. Analysis of the combined density-of-states function epsilon sub 2 E squared yields 3.0 eV for the energy gap between bonding and antibonding sp states for both compounds. Also, from interpretation of epsilon sub 2 together with epsilon sub 2 E squared the energy separation between the Fermi level E sub F and the bottom of the minority spin e-band and the distance of the valence band edge from E sub F are obtained. (Author)