PRESSURE AND FIELD-DEPENDENCE OF SUPERCONDUCTIVITY IN RB3C60

Direct measurements of the pressure dependence of the superconducting transition temperature T(c) for single-phase Rb3C60 provide for the first time substantial evidence that T(c) in A3C60 compounds may be a universal function of the lattice constant (inter-C60 spacing). Determination of the lower (H(c1)) and upper (H(c2)) critical fields, and consequently the superconducting penetration depth and coherence length, is also reported. Compared to K3C60, the measured quantities are consistent with a 15% larger electronic-state density in Rb3C60 arising from a greater inter-C60 spacing in this compound.