2008/11/24 by W. Fan, Fan, W.
Physics and Astronomy · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Superconductivity (cond-mat.supr-con) #cond-mat.mtrl-sci #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.0811.3813
Accepted by International of Modern Physics B (13pages, 2eps figure)
arxiv created 2008/11/24 · arxiv updated 2009/12/01
The numerical calculations of the standard Eliashberg-Nambu strong coupling theory and a formula of isotope effect derived in this paper provide direct evidences that an-harmonic vibrations of lattice enhance isotope effect with anomalous coefficient α>1/2. The results in this paper explain very well the wide distributed α values for the samples with different ratios of substitutions of 12C by 13C of fulleride superconductor Rb3C60. The calculations of isotope effects indicate that the intra-molecule radial modes have more important contributions to superconductivity than the intra-molecule tangential modes with higher phonon frequencies