Observation of a new excitation in the mixed-valent state of YbInCu_4

Garner, S. R.; Rodriguez, Y. W.; Schlesinger, Z.; Bucher, B.; Fisk, Z.; Sarrao, J. L.

Observation of a new excitation in the mixed-valent state of YbInCu_4

Authors

Description

Infrared measurements are used to obtain conductivity as a function of temperature and frequency in YbInCu_4, which exhibits an isostructural transition to a mixed-valent state at T_v \simeq 42 K. In addition to a gradual loss of spectral weight with decreasing temperature extending up to 1.5 eV, sharp resonances appear in the mixed-valent state at 0 and 0.25 eV . These features may be key to understanding both YbInCu_4 and the nature of the mixed-valent Kondo state.
4 pages, 3 postscript figures