ABINITIO INVESTIGATION OF MICROSCOPIC ENHANCEMENT FACTORS IN TUNING THE MAGNETOOPTICAL KERR EFFECT

The microscopic quantities that determine the magnitude and frequency position of peaks in the Kerr rotation spectrum are studied on the basis of first-principles band-structure theory. The transition metals Fe, Co and Ni serve as model systems. The magnitude of the magneto-optical Kerr effect (MOKE) is basically brought about by the spin-orbit (SO) coupling strength and it is shown that the Kerr rotation scales linearly with the SO-coupling. Exchange splitting (or magnetization) is found to influence the Kerr effect in a rather complicated way: enlarging the magnetization can both enhance and diminish spectral peaks. A strong effect is found for the dependence of the position of spectral peaks on the lattice spacing: a 3 to 6% increase in lattice parameters can lead to shifts of about 1 eV of the main MOKE peak.