We present combined experimental and theoretical results for the magnetic circular dichroism (MCD) in resonant $4f$ photoemission (RPE) from Tb metal in the perpendicular geometry at different photon energies across the whole of the $M_{4,5}$ resonance. The atomic calculations, which take into account the full multiplet structure and the coherent second-order optical process, give excellent agreement with new experimental results for the resonant photoemission decay. The angular dependence of the MCD-RPE and its strong spin polarization in the $M_5$ region are also reported. For a single-configuration state the variations in the spectral shape are found to be stronger as a function of angle than as a function of photon energy. Due to the presence of the multiplet structure in the intermediate state ${3d}^9{4f}^9$ the coherent second-order optical process is essential for a correct description of the RPE. While the analysis of the spectra in parallel geometry yields accurate values of the spin-orbit, Coulomb, and exchange interactions, only the angle dependent RPE provides the phase factors of the emitted photoelectron.

• Received 19 May 2003

DOI:https://doi.org/10.1103/PhysRevB.68.104408