Hard X-ray valence-band and core-level photoelectron spectroscopy of strongly correlated electron systems

Valence-band and core-level photoelectron spectroscopy (PES) has been successfully used to study strongly correlated electron systems such as CeRhAs, YbInCu4, and YbB12 at photon energies of h ν ∼ 6 keV with high-energy resolution, Δ E ∼ 160 – 270 meV . Due to the long penetration depth of electrons with high kinetic energy, the photoelectron spectra obtained reflect the bulk electronic properties. The merits of utilizing both hard X-ray PES and VUV–SX PES to investigate the electronic states of strongly correlated electron systems in the bulk are presented.