Abstract
Optical reflectivity experiments have been conducted on single crystals of the Kondo insulator in order to obtain its optical conductivity, σ(ω). Upon cooling below 70 K, a strong suppression of σ(ω) is seen in the far-infrared region, indicating the opening of an energy gap of This gap development is coincident with a rapid decrease in the magnetic susceptibility, which shows that the gap opening has significant influence on magnetic properties. A narrow, asymmetric peak is observed at in σ(ω), which is attributed to optical transitions between the Yb -derived states across the gap. In addition, a broad peak is observed at This peak is attributed to transitions between Yb -derived states and the band, and is reminiscent of similar peaks previously observed for rare-earth hexaborides.
- Received 12 May 1998
DOI:https://doi.org/10.1103/PhysRevB.58.R7496
©1998 American Physical Society