Kondo Semiconductor YbB12 Research Articles

Optical study of c–f hybridization states in mixed-valent Yb compounds: metallic YbAl3 vs semiconducting YbB12

Abstract We have measured the optical conductivity spectra σ(ω) of YbB12 and YbAl3, which are typical mixed-valent Yb compounds. The measured σ(ω) spectra in the mid-infrared region are quite similar for the two compounds, with a pronounced peak centered near 0.2 eV . This result demonstrates that the Kondo semiconductor YbB12 and the highly metallic YbAl3 share very similar electronic structures near the Fermi level, in spite of their very different transport properties at low temperatures. This observation is discussed in terms of c–f hybridization states in these compounds.