## Determining the crystal-field ground state in rare earth Heavy Fermion materials using soft-x-ray absorption spectroscopy

Hansmann, P.
Severing, A.
Hu, Z.
Haverkort, M. W.
Chang, C. F.
Klein, S.
Tanaka, A.
Hsieh, H. H.
Lin, H. -J.
Chen, C. T.
##### Description
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 $M_{4,5}$ 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 CePd$_2$Si$_2$, thereby settling an existing disagreement about its crystal-field ground state.
##### Keywords
Condensed Matter - Strongly Correlated Electrons