Infrared spectra of a K4C60 single-phase thin film have been measured between room temperature and 20 K. At low temperatures, the two high-frequency T1u modes appear as triplets, indicating a static D2h crystal-field stabilized Jahn-Teller distortion of the C604- anions. The T1u(4) mode changes into a known doublet above 250 K, a pattern which could have three origins: a dynamic Jahn-Teller effect, static disorder between "staggered" anions, or a phase transition from an orientationally ordered phase to one where molecular motion is significant.
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Feb 1 2002|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics