Orientational ordering and electron-phonon interaction in K3C60 superconductor

Abstract

The normal state and superconducting state properties of a well characterized K3C60 superconductor are studied in terms of the combined measurements of x-ray diffraction, Raman scattering, magnetization, and resistivity by using the same sample synthesized by the wet chemical method. The temperature downshift of about 50 K is observed for the orientational ordering from pristine C60 to the synthesized sample based on the anomalies of both the resistivity and phonon frequency. When entering the superconducting state, the enhanced self-energy effects are reflected from the softening and broadening of the phonon modes. The obtained electron-phonon interaction strength of 0.63 in the superconducting state accounts well for the transition temperature of 18 K in K3C60 and the plausible Coulomb pseudopotential and expected isotope exponent.