Open AccessMECHANISM FOR THE ORIENTATIONAL PHASE TRANSITION OF K3C60
Author(s) -
Hong-Nian Li,
Yang Xu,
Bao Shi-Ning,
Haiyang Li,
Wu Tai-Quan,
X. Chen,
Qian Huang,
Kurash Ibrahim,
Fengqin Liu
Publication year - 2001
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.50.2456
Subject(s) - materials science , phase transition , condensed matter physics , synchrotron radiation , thermal conduction , phase (matter) , molecule , spectral line , conduction band , electronic band structure , crystal structure , molecular physics , crystallography , physics , optics , chemistry , electron , quantum mechanics , astronomy , composite material
Conduction band structure of K3C60 single crystal films was studied at temperatures near 200 K. Band dispersions along the [111] direction could be observed at 190 K using synchrotron radiation photoemission spectra technique. When the sample temperature increased to 220 K, most subpeaks of the conduction band vanished and the dispersions could not be observed. This result coincides with the existence of an orientational phase transition occurring at 200 K. The fcc nearest-neighbor antiferromagetic Ising model was adopted to analyze the temperature dependence of the band structure. The phase transition is due to the one-dimensional-disordered structure (1DDS) at lower temperatures, which turns to a mixture of bi-directional structure domains and disordered molecules at higher temperatures. The number of disordered molecules was deduced to be about 40 percent of the total molecules at 220 K.