OPTICAL AND MAGNETOOPTICAL PROPERTIES OF MNBI FILM

The spectral features of Kerr rotation and ellipticity of MnBi film ha ve been found to greatly change with temperature from 85 to 475 K, and the Kerr rotation at 700 nm increases over 50%. And the complex refra ctive index at room temperature and the dielectric and conductivity te nsors at 85, 300, and 475 K have been determined with the reflectance of an opaque film, the transmittance of a semitransparent film and the Kerr effect. There are two distinct peaks in the omega sigma(xy)(v) s pectrum, corresponding well to that of Ken rotation. By comparing thos e results with the reported calculations, it becomesxyn clear that the Ken rotations originate principally from the interband transitions of Mn 3d down arrow electrons ((h) over bar omega<2.5 eV) and of Mn 3d u p arrow electrons ((h) over bar omega>2.5 eV). And the changes of the exchange splitting and the spin-orbit interaction strength are respons ible for the strong temperature dependence of Kerr effect. Specific Fa raday spectra at different temperatures have also been calculated with the above optical and dielectric constants and are much different fro m the reported data.