MAGNETIZATION STUDIES OF Rb₃C₆₀ IN SUPERCONDUCTING STATE

Abstract

We present the results of magnetic measurements in fields up to 50 kOe for superconducting Rb 3 C 60. The temperature dependence of upper H c 2 critical magnetic field is determined, from which the zero temperature value Hc2(0)=465±50 kOe is evaluated. The magnitudes of penetration depth and coherence length are calculated as ξ(0)=26.7±3 Å; λ L (0)=2150±100 Å at zero temperature. The temperature dependence of ξ(T) and λ L (T) for T≧23 K is in good agreement with the Ginzburg-Landau theory. The critical current densities for different temperatures are calculated, showing a strong decrease of Jc with increasing temperature for T≤7 K . Two regions of fading critical current density on a magnetic field dependence are found.

Mixed-state parameters and vortex pinning in single-crystallineK3C60fullerene superconductors

“…Similar results were previously observed on other superconducting compounds. 8,39 At higher temperatures the same general behavior is found, but J c suddenly becomes smaller than the resolution of our experimental device at some characteristic value of the external magnetic field ͑Fig. 9͒.…”

Solid State and Magnetic Properties of Pure, Intercalated and Superconducting Fullerenes

“…According to Ref. [198] the temperature dependence of the coherence length and the penetration depth in Rb 3 C 60 can be well described by Ginzburg-Landau theory in the temperature range 0· 85 < T/T c < 1. A strong scatter of the experimental data is found for H c2 (0) and H c2 (Table 2).…”

“…A large number of experiments was made to determine the upper critical field for crystalline [169,175,181, and powdered [159, 161, 179, 180, 183-85, 190, 194-98] fullerenes as well as for thin films [176] using different techniques such as magnetisation [161,179,180,184,198], ac-susceptibility [190,195], transport [176,197], rf-absorption [196], etc. Almost all measurements were done on K 3 C 60 and Rb 3 C 60 and only a few results are available on each of RbCs 2 C 60 [184], K 2 CsC 60 and Rb 2 CsC 60 [199] and Ba 6 C 60 [200].…”

Magnetic properties of fullerene superconductors

“…However, as we discussed before, the qualitative character of the temperature and magnetic field dependence of J c is believed to be correct. It has been shown for Rb 3 C 60 [151] and RbCs 2 C 60 [180,181] powders that the temperature dependence of J c follows the empirical equation (9) with n = 3-5 for both compounds. These results are shown in figure 12.…”

“…The double logarithmic dependence of the critical current density on [1 − (T /T c ) 2 ] at different magnetic fields. (From[151]). …”