Electronic structure of LaIrIn5 and f-electron character in its related Ce-115 compounds

LaIrIn 5 is a reference compound of the heavy-fermion superconductor CeIrIn 5 . The lack of f electrons in LaIrIn 5 indicates that there should not be any f electron participating in the construction of its Fermi surface. Thus the electronic structure comparison between LaIrIn5 and CeIrIn5 provides a good platform to study the properties of f electrons. Here angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations are performed to study the electronic structures of LaIrIn 5 and CeIrIn 5 . We find the valence band structures of the two materials are similar to each other, except for the absence of f bands in LaIrIn 5 . By analyzing the Fermi crossings of the three conduction bands of the two materials quantitatively, we find the volumes of the electron pockets α and β around the M′ point become larger from LaIrIn 5 to CeIrIn 5 , while the hole pocket γ around the Γ′ point becomes smaller. Together with the calculation results, we confirm that this is mainly originated from the f-electron contribution, while the lattice-constant difference between LaIrIn 5 and CeIrIn 5 only has a finite influence. We also give a summary of the f-electron character in its related Ce-115 heavy fermion compounds. Our results may be essential for the complete microscopic understanding of the 115 compounds and the related heavy-fermion systems.