Magnetic relaxation in pulse-magnetized high-temperature superconductors

Abstract A magnetic filed relaxation at the center of a pulse-magnetized single-domain Y–Ba–Cu–O superconductor at 78 K has been studied. In case of a weak magnetization, the magnetic flux density increases logarithmically and normalized relaxation rate defined as S  = −d(ln B )/d(ln t ) is negative ( S  = −0.037). When an external magnetic field magnitude increases, the relaxation rate first decreases in absolute value, then changes sign (becomes positive, S  > 0) and after reaching some maximum finally reduces to a very small value. Non-monotonous dependence of S vs. H a is explained by a non-homogeneous local temperature distribution during a pulse magnetization.