Magneto-optical properties of MnBi1-xSbx films

We have grown MnBi_1-xSb_x alloy films on mica and glass substrates under UHV conditions, and performed a systematic study of the structural, magnetic and magneto-optic properties on films in the concentration range 0⩽x⩽0.4. Sharp Reflection High Energy Electron Diffraction (RHEED) patterns were observed for samples grown on mica substrates, indicating epitaxial growth. X-ray diffraction patterns of MnBi_1-xSb_x grown on glass substrates show these films to be highly textured, with the c-axis parallel to the substrate normal. We found that only samples with Mn concentration above 50 at.% exhibited good magneto-optical properties. Perpendicular magnetization and Kerr rotation larger than 0.5° were observed for samples with Sb concentration less than 8 at.% in mica and 4 at.% on glass. For larger concentrations of Sb, the coercivity increased rapidly while Kerr rotation decreased. Samples grown on both types of substrates showed an increase in the Kerr rotation and ellipticity with decreasing light wavelengths. The off-diagonal E-field reflectivity, r_xy, which describes the magneto-optic efficiency of the sample, is larger than that reported for TbFeCo layers