MANIPULATION OF THE SPIN-ORBIT-COUPLING USING THE DIRAC-EQUATION FOR SPIN-DEPENDENT POTENTIALS

A scheme is presented that allows one to decompose the spin-orbit coup ling operator into two parts within calculations based on the Dirac eq uation for spin-dependent potentials. The first term lifts energetic d egeneracies but leaves the spin as a good quantum number, while the se cond term causes hybridization of states with a different spin charact er. To investigate the importance of these terms and of the mechanism connected to them a number of model calculations for the dispersion re lation, the spin-orbit-induced orbital magnetic moment, and the magnet o-optical Kerr effect in several transition metal systems have been pe rformed by retaining just one of them. In all cases studied it was fou nd that the first term is by far the most important source for spin-or bit-induced phenomena.