Optical conductivity [σ(ω)] of YbCu 2 Ge 2 has been measured at external pressures (P ) to 20 GPa, to study the P evolution of f electron hybridized states. At P =0, σ(ω) shows a marked mid-infrared (mIR) peak at 0.37 eV, which is due to optical excitations from f 14 (Yb 2+ ) state located below the Fermi level. With increasing P , the mIR peak shows significant shifts to lower energy, reaching 0.18 eV at P =20 GPa. This result indicates that the f 14 energy level increases toward the Fermi level with P . Such a shift of the f electron level with P has been expected from theoretical considerations, but had never been demonstrated by spectroscopic experiment under high P . The obtained results are also analyzed in terms of the P evolution of the conduction-f electron hybridization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.