Persistent currents and magnetic flux trapping in fragments of carbon deposits containing multiwalled nanotubes

Abstract

It is found that the magnetization curves of samples of fragments of cathode carbon deposits with a high content of multiwalled nanotubes exhibit a pronounced irreversible character, attesting to the induction of persistent currents in the samples and to magnetic flux trapping, as happens in a multiply connected superconducting structure. A decrease of the trapped flux in time could not be observed at low (helium) temperatures with a measurement time of about 20 h. For intermediate (~30K) and room temperatures the trapped magnetic flux decays slowly with characteristic relaxation times of the order of 150 and 15 h, respectively.