Abstract
We have measured the optical conductivity of where the system evolves from a Kondo semiconductor at to a nonmagnetic metal at For exhibits a clear energy gap with an onset at and a shoulder at 38 meV. As x increases, the gap is rapidly filled in from the bottom, while the shoulder remains at up to These results suggest that Lu substitution into produces an in-gap band, but the characteristic energy for the gap remains unchanged in a wide range of x. Spectral evolutions of a characteristic mid-infrared peak, which results from Yb -derived states near the Fermi level, suggest a strong coupling of Yb electrons with conduction electrons.
- Received 7 August 2000
DOI:https://doi.org/10.1103/PhysRevB.62.R13265
©2000 American Physical Society