Electronic structure study of LaCoIn 5 and its comparison with CeCoIn 5
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 LaCoIn 5 , which is a non- f reference compound of the heavy-fermion superconductor CeCoIn 5 . Our angle-resolved photoemission spectroscopy study of the three-dimensional Fermi surface and band structure of LaCoIn 5 highlights the rather three-dimensional electronic character of this compound. The conduction bands of LaCoIn 5 are almost identical to that of CeCoIn 5 , though obvious differences can be found in the low-energy electronic structure. Finally, we give a quantitative analysis of the Fermi pocket change in LaCoIn 5 and CeCoIn 5 , which may be helpful for understanding the important “large” and “small” Fermi surface issue in heavy-fermion compounds.