Calculated magneto-optical Kerr spectra of XPt(3) compounds (X=V,Cr,Mn,Fe and Co)

The magneto-optical spectra of the XPt(3) compounds (with X=V, Cr, Mn, Fe and Co) are calculated for their ferromagnetic phase in the AuCu3 crystal structure, using density-functional band-structure theory. Large polar Kerr effects are predicted for several of these compounds, with-for a reasonable spectral broadening of 0.4 eV-maximum Ken rotations of -1.5 degrees for MnPt3 and -1.0 degrees, -1.1 degrees for CoPt3 and FePt3 respectively. The Ken spectra of VPt3, CrPt3 and MnPt3 with (001) magnetization are found to be very similar in shape, as are also those of FePt3 and CoPt3. The origin of the large Ken effect in the XPt(3) alloys is shown to be caused by the spin-orbit coupling strength of Pt. A magnetic moment of moderate size on the 3d atom suffices in these materials to already create an appreciable Ken effect. The influence of the optical transition matrix elements, magnetic moments and spin-orbit coupling strength on each of the constituent atoms are furthermore analysed. The orientation dependence of the polar Ken spectra of some of the XPt(3) compounds are investigated by calculating in addition the polar Ken spectra of some compounds for the (111) magnetization axis. The Ken spectra of the (111) magnetization are found to be practically identical to that of the (001) magnetization.