Electronic structure of CenMmIn2m+3n, where n = 1, 2; m = 0, 1;M = Co, Rh or Ir: experiment and calculations

Abstract

We present a detailed study of the electronic structure of the CenMmIn2m+3n (M = Co, Rh, Ir; n = 1, 2 and m = 0, 1) series of Ce intermetallic compounds and of the reference LaIn3 compound. The ground state of these heavy-fermion (HF) materials can be tuned between antiferromagnetic (AF) and superconducting (SC), with pressure or doping as the tuning parameter. Performing the x-ray photoelectron spectroscopy (XPS) measurements on the Ce 3d core levels as well as on the valence band states we analyse the dependence of both the Ce 4f band character and physical properties on the kind of transition metal atom M and on the number of CeIn3 layers intervened by the MIn2 layers in the investigated family of compounds. We draw a parallel between the XPS valence band spectra and ab initio band structure calculations based on the full-potential linearized augmented plane-wave (FP-LAPW) method. We analyse changes in valence band states within the whole family of materials. We compare the experimental magnetic moments on Ce atoms with the theoretical ones calculated within different approximations for exchange–correlation potential. Finally, we have shown that the Ce 4f electrons participate in bonding formation for all investigated compounds. Our study indicates that the observed changes in the 4f band on-site hybridization energy result from the reconstruction of the charge density distribution driven by transition metal atoms inserted into the CeIn3 structure.