SUM-RULES FOR MAGNETIC DICHROISM IN RARE-EARTH 4F-PHOTOEMISSION

We present new sum rules for magnetic dichroism in spin polarized photoemission from partly filled shells which give the expectation values of the orbital and spin magnetic moments and their correlations in the ground state. We apply this to the 4f photoemission of rare earths, where the polarization effects are 2 orders of magnitude larger than in 3d transition metals. The very strong dichroism in the 4f electron yield opens new perspectives for the characterization of magnetic rare earth surfaces and thin films