Magnetic flux relaxation in a pulse-magnetized Y-Ba-Cu-O superconductor

Trapped flux relaxation at the center of a single-domain Y-Ba-Cu-O superconductor upon pulsed field magnetization has been studied at T = 78 K. In the case of a weakly magnetized sample, the induction increases according to a logarithmic law and the creep rate (defined as S = −dlnB/dlnt) is negative. As the amplitude H a of the magnetizing field grows, the creep rate decreases, changes sign, passes through a maximum, and tends to zero. The nonmonotonic behavior of S(H a ) is explained by a nonuniform radial distribution of the temperature during the magnetization pulse.