We infer that soft-x-ray absorption spectroscopy is a versatile method for the determination of the crystal-field ground state symmetry of rare earth Heavy Fermion systems, complementing neutron scattering. Using realistic and universal parameters, we provide a theoretical mapping between the polarization dependence of Ce M4,5 spectra and the charge distribution of the Ce 4f states. The experimental resolution can be orders of magnitude larger than the 4f crystal field splitting itself. To demonstrate the experimental feasibility of the method, we investigated CePd2Si2, thereby settling an existing disagreement about its crystal-field ground state.
@article{arxiv.0710.2778,
title = {Determining the crystal-field ground state in rare earth Heavy Fermion materials using soft-x-ray absorption spectroscopy},
author = {P. Hansmann and A. Severing and Z. Hu and M. W. Haverkort and C. F. Chang and S. Klein and A. Tanaka and H. H. Hsieh and H. -J. Lin and C. T. Chen and B. Fåk and P. Lejay and L. H. Tjeng},
journal= {arXiv preprint arXiv:0710.2778},
year = {2008}
}