We have performed muon spin relaxation (μSR) measurements of the magnetic field penetration depth λ in Rb3C60, K3C60, and Na2CsC60. In a plot of Tc versus the muon spin relaxation rate σ(T → 0) ∝ λ-2, we observe a monotonic variation, following a roughly linear relation Tc ∝ σ. Assuming a clean-limit situation, where λ-2 ∝ ns/m* (carrier density / effective mass), the μSR results imply a variation Tc ∝ ns/m*, opposite to the variation expected in a simple band picture where a decreasing band width (increasing m*) with increasing lattice constant (increasing Tc) would have reduced ns/m*.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering