LOW-TEMPERATURE MAGNETIZATION AND FLUX-CREEP STUDIES OF A DYBA2CU3O7 SINGLE-CRYSTAL WITH A VIBRATING REED

Magnetization measurements have been performed on a high-temperature D yBa2Cu3O7 superconducting crystal in the magnetic field range 0 T less than or equal to mu(0)H less than or equal to 7 T parallel to the c-a xis and temperature range 0.1 K less than or equal to T less than or e qual to 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 t he analytical result for a type-II superconducting strip in perpendicu lar magnetic field with constant critical current density. We have als o measured the time dependence of the magnetization at times 1 s < t l ess than or equal to 10(4) s and at a field mu(0)H = 1 T We obtain for the normalized relaxation rate S = (1/M(irr))dM/d In t = 0.02 + T/700 K at T less than or equal to 20 K. The value S(0) is similar to that observed for very different high-temperature superconductors.