Determination of Spin- and Orbital-Moment Anisotropies in Transition Metals by Angle-Dependent X-Ray Magnetic Circular Dichroism

Angle-dependent x-ray absorption spectroscopy in strong magnetic fields is shown to yield precise site specific information about spin and orbital moments in highly anisotropic $3d$ transition metal systems. A new angle averaging spin sum rule allows for the separate determination of spin and magnetic dipole moments in lower than cubic site symmetry. The microscopic origin of the magnetocrystalline anisotropy can be probed directly through the angular dependence of the orbital moment.