Moderate hybridization effects revealed by ARPES in heavy-fermion Ce2IrIn8

We utilized high-resolution resonant angle-resolved photoemission spectroscopy (ARPES) to study the band structure and hybridization effect of the heavy-fermion compound Ce2IrIn8. We observe a nearly flat band at the binding energy of 7 meV below the coherent temperature Tcoh ~ 40 K, which characterizes the electrical resistance maximum indicating the onset temperature of hybridization. However, the Fermi vector kF and the Fermi surface (FS) volume have little change around Tcoh, challenging the widely believed evolution from a high-temperature small FS to a low-temperature large FS. Our experimental results of the band structure fit well with the density functional theory plus dynamic mean-field theory (DFT+DMFT) calculations.