MAGNETIZATION STUDIES OF RB3C60 IN SUPERCONDUCTING STATE

We present the results of magnetic measurements in fields up to 50 kOe for superconducting Rb3C60. The temperature dependence of upper H(c2) critical magnetic field is determined, from which the zero temperatur e value H(c2)0 = 465 +/- 50 kOe is evaluated. The magnitudes of penetr ation depth and coherence length are calculated as xi(0) = 26.7 +/- 3 angstrom; lambda(L)(0) = 2150 +/- 100 angstrom at zero temperature. Th e temperature dependence of xi(T) and lambda(L)(T) for T greater-than- or-equal-to 23 K is in good agreement with the Ginzburg-Landau theory. The critical current densities for different temperatures are calcula ted, showing a strong decrease of J(c) with increasing temperature for T less-than-or-equal-to 7 K. Two regions of fading critical current d ensity on a magnetic field dependence are found.