Phys. Rev. Lett. 72, 3092-3095 (1994)

[Issue 19 - May 1994 ]

Temperature dependence of the magnetic field penetration depth in Rb₃C₆₀ measured by ac susceptibility

A. M. Neminsky, P. N. Nikolaev, and D. V. Shovkun

Institute of Solid State Physics, 142432 Chernogolovka, Moscow district, Russia

E. E. Laukhina and E. B. Yagubskii

Institute of Chemical Physics, 142432 Chernogolovka, Moscow district, Russia

The temperature dependence of the magnetic field penetration depth lambda (T) is determined down to 0.2T_c by the ac-susceptibility measurements on the Rb₃C₆₀ fine powder with small, about 1 K, variation in the grains' superconducting transition temperatures. The lambda (T) temperature dependence is exponential at low temperatures, which allows us to determine the energy gap Delta ₀=1.7k_BT_c. Deviations of the experimental dependence lambda (T) from BCS are small and can be explained by strong-coupling theory.

ї1994 The American Physical Society

PACS: 74.25.Ha, 74.70.Wz