Abstract:

Heavy fermion compound is a classical type of correlated materials, encompassing unconventional superconductivity, strange metal, quantum criticality, magnetic order, heavy electronic states, correlated topological states, etc, in which 4f electrons play a critical role. With the advancement of high-resolution ARPES measurements and MBE thin film growth techniques, direct observation of the band dispersion and spectral weight of 4f electrons in momentum/energy space has become possible, providing spectroscopic insight for understanding correlated electronic states and novel quantum phenomena. In this review paper, we summarized the electronic studies of several typical heavy fermion compounds and thin films, including Ce-115 families, CuCu₂Si₂, CeRh₆Ge₄ and Ce films, etc. The experimental results provide direct evidence to understand the temperature evolution of heavy electronic states, energy/moment-dependent Kondo hybridization, the interplay of heavy electronic state with superconductivity, the competition between Kondo effect with other quantum states and the dimensionality tuning of 4f electrons.

Key words: heavy fermion materials, Kondo effect, electron correlation effect, angle-resolved photoemission spectroscopy, dimensionality tuning