Abstract
Optical conductivity of and have been measured at external pressures to 10 GPa and at low temperatures to 6 K. Regarding , at ambient pressure the main feature in is a Drude peak due to free carriers. With increasing pressure, however, a characteristic midinfrared (mIR) peak rapidly develops in , and its peak energy and width increase with pressure. These features are consistent with an increased conduction ()- electron hybridization at high pressure and show that pressure has tuned the electronic state of from very weakly to strongly hybridized ones. As for , in contrast, a marked mIR peak is observed already at ambient pressure, indicating a strong hybridization. At high pressures, however, the mIR peak shifts to lower energy and becomes diminished and seems to merge with the Drude component at 10 GPa. Namely, and exhibit some opposite tendencies in the pressure evolution of and electronic structure. These results are discussed in terms of the pressure evolution of hybridized electronic states in Ce and Yb compounds, in particular in terms of the electron-hole symmetry often considered between Ce and Yb.
- Received 10 August 2019
- Revised 15 October 2019
DOI:https://doi.org/10.1103/PhysRevB.100.195112
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