Crystal field and Kondo effect in CeMIn$_{5}$, M=Rh, Ir, and Co: a polarized soft XAS and neutron scattering study

We have determined the crystal-field scheme and the 4f conduction electron interaction in CeMIn5, M= Rh, Ir, and Co with linear polarized soft X-ray absorption and neutron scattering. Soft-x-ray absorption spectroscopy (XAS) at the Ce M4,5 edges can be used as a complementary technique to neutron scattering. XAS is highly sensitive to the symmetry of the initial state and through the polarization dependence direct information about the Jz admixtures of the ground state wave function can be obtained. Sensitivity to higher lying states is achieved by thermally populating those states. From soft XAS we find that the ground state wave functions of the CeMIn5 have increasingly Jz=3/2 character when going from M=Rh, Ir and largest for Co, and we find from the neutron line widths and the 4f0 contribution to the M4,5 edges that the 4f conduction electron interaction increases in the same sequence.