Magnetization relaxation in superconducting fulleride K3C60 single crystals

Abstract

Magnetic relaxation processes in superconducting fulleride K3C60 are investigated on monocrystalline samples in a wide range of temperatures and magnetic fields. A logarithmic time dependence M(t) of magnetization is observed in samples with 100% of superconducting phase. The normalized relaxation rate increases with temperature in the entire range of magnetic fields. The flux creep activation energy ranges from 10 to 80 meV, and its temperature dependence has a peak. It has been concluded from the results of measurements on samples with nonideal stoichiometry that inhomogeneities strongly affect the relaxation processes and can mask the logarithmic dependence M(t) completely.

Muon spin rotation and SQUID investigation of superconductivity in(NH3)xNaKRiccò1, Shiroka2, Zannoni3 et al. 2003Phys. Rev. B3020View full textAdd to dashboardCite

“…In spite of many previous measurements of the lower critical field by SQUID magnetometry in fullerides, 7,8,11,12,13,14,15,16,17,18 its precise determination is still controversial due to considerable experimental difficulties. The simplest way to measure H c1 consists in observing the field at which the M = M (H) curve starts to deviate from linearity.…”