Effect of neutron irradiation on irreversible torque in superconducting Bi 2Sr 2CaCu 2O x single crystals

Abstract

Torque magnetometry is used to measure the effect of fast neutron irradiation on the magnitude and the anisotropy of the critical current in Bi 2Sr 2CaCu 2O x single crystals. Measurements have been performed in the temperature range from 4.2 K to the critical temperature in magnetic fields up to 1.76 T. A large enhancement of the critical current has been observed after neutron irradiation. This effect increases considerably at high temperatures. Irradiation has also some effect on the anisotropy of the critical current. An exponential decrease of the critical current with temperature is observed for both irradiated and unirradiated samples. Such behavior results from the nonlinear dependence of the effective activation energy on the current density.