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Register a new userObservation of a new excitation in the mixed-valent state of YbInCu_4
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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.
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