Isotope effect in superconductingRb3C60

Abstract

Measurements of the superconducting ${\mathit{T}}_{\mathit{c}}$ and Raman spectra in isotopically modified ${\mathrm{Rb}}_3$ ${\mathrm{C}}_{60}$ are reported. A decrease in ${\mathit{T}}_{\mathit{c}}$ of 0.65±0.10 K in samples with (75±5)% substitution of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ yields an exponent of α=0.37±0.05. This interpreted as evidence for phonon-mediated pairing.