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Oscillatory electron phonon coupling in Pb/Si(111) deduced by temperature-dependent quantum well states
Zhang Yan-Feng (张艳锋), Jia Jin-Feng (贾金锋), Han Tie-Zhu (韩铁柱), Tang Zhe (唐喆), Shen Quan-Tong (沈全通), Guo Yang (郭阳), Xue Qi-Kun (薛其坤)
Chinese Physics,
2005, 14 (9):
1910-1914.
DOI: 10.1088/1009-1963/14/9/041
Photoemission study of atomically flat Pb films with a thickness from 15 to 24 monolayers (ML) have been performed within a temperature range 75--270K.Well-defined quantum well states (QWSs) are observed, which exhibit interesting temperature-dependent behaviours. The peak position of the QWSs shifts towards higher binding energy with increasing substrate temperature,whereas the peak width broadens linearly due to enhanced electron--phonon coupling strength ($\lambda$). An oscillatory $\lambda$ with a period of 2ML is deduced. Preliminary analysis shows that the oscillation can be explained in terms of the interface induced phase variations, and is thus a manifestation of the quantum size effects.
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