Electronic structure study of LaCoIn5 and its comparison with CeCoIn5

A central key to understanding heavy-fermion systems involves revealing how itinerant low-energy excitations emerge from local f moments. An effective way to understand the f-electron behavior is to compare the electronic structure of f-electron compounds with a reference isostructural compound with no f electrons. Here we present a systematic electronic structure study of LaCoIn₅, which is a non-f reference compound of the heavy-fermion superconductor CeCoIn₅. Our angle-resolved photoemission spectroscopy study of the three-dimensional Fermi surface and band structure of LaCoIn₅ highlights the rather three-dimensional electronic character of this compound. The conduction bands of LaCoIn₅ are almost identical to that of CeCoIn₅, though obvious differences can be found in the low-energy electronic structure. Finally, we give a quantitative analysis of the Fermi pocket change in LaCoIn₅ and CeCoIn₅, which may be helpful for understanding the important "large" and "small" Fermi surface issue in heavy-fermion compounds.