The diagonal component (Formula presented) and off-diagonal component (Formula presented) of the complex dielectric tensor for the ferromagnetic compound NiMnSb are determined using ex situ spectroscopic ellipsometry and magneto-optic analysis over the spectral range from 0.7 to 6.2 eV. The effects of the overcoat on the raw data are removed by the analysis. First, the complex (Formula presented) of thin-film NiMnSb were determined by ex situ spectroscopic ellipsometry; then (Formula presented) was determined by analyzing Kerr rotation and ellipticity data using the determined (Formula presented) data. Lorentz oscillators were used to model peaks seen in the (Formula presented) spectra. The diagonal dielectric component (Formula presented) is dominated by free-carrier effects below 1.15 eV, and dominated by interband transitions above 2.0 eV. The center energies of the Lorentz oscillators are consistent with the calculated band structure and minority-spin optical conductivity of NiMnSb. Joint density of states and optical conductivity calculated from (Formula presented) data with free-carrier effects removed shows onset energies at ∼0.6 and ∼0.2 eV, respectively. From a study of the (Formula presented) and (Formula presented) spectra, the Kerr rotation peak at lower energy is determined to be due to combined contributions from: (1) a crossover between the free-carrier effect and interband transitions, and (2) transitions involving spin-orbit coupling. The high-Kerr rotation peaks at higher energies result exclusively from transitions involving spin-orbit coupling.
|Original language||English (US)|
|Number of pages||7|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jan 1 1999|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics