Evolution of ground-state wave function in CeCoIn5 upon Cd or Sn doping

We present linear polarization-dependent soft-x-ray absorption spectroscopy data at the Ce M_4,5 edges of Cd- and Sn-doped CeCoIn₅. The 4f ground-state wave functions have been determined for their superconducting, antiferromagnetic, and paramagnetic ground states. The absence of changes in the wave functions in CeCo (In_1-xCd_x)₅ suggests that the 4f-conduction-electron (c f) hybridization is not affected by global Cd doping, thus supporting the interpretation of magnetic droplets nucleating long-range magnetic order. This is contrasted by changes in the wave function due to Sn substitution. Increasing Sn in CeCo (In_1-ySn_y)₅ compresses the 4f orbitals into the tetragonal plane of these materials, suggesting enhanced c f hybridization with the in-plane In(1) atoms and a homogeneous altering of the electronic structure. As these experiments show, the 4 f wave functions are a very sensitive probe of small changes in the hybridization of 4f and conduction electrons, even conveying information about direction dependencies.