Low-temperature magnetization and flux creep studies of a DyBa 2Cu 3O 7 single crystal with a vibrating reed

Abstract

Magnetization measurements have been performed on a high-temperature DyBa 2Cu 3O 7 superconducting crystal in the magnetic field range 0 T ≤ μ 0 H ≤ 7 T parallel to the c-axis and temperature range 0.1 K ≤ T ≤ 30 K with the vibrating reed technique. No anomalous behavior of the magnetization was observed at the antiferromagnetic transition. The field dependence of the virgin magnetization curve M( H) follows the analytical result for a type-II superconducting strip in perpendicular magnetic field with constant critical current density. We have also measured the time dependence of the magnetization at times 1 s < t ≤ 10 4 s and at a field μ 0 H = 1 T. We obtain for the normalized relaxation rate S = (1/ M irr)d M/d 1n t = 0.02 + T/700 K at T ≤ 20 K. The value S(0) is similar to that observed for very different high-temperature superconductors.