Abstract
The magnetic hysteresis curve of YBa2(Cu1-xFex)3Oy(0≤x≤0.08) prepared by two kinds of heat treatments was measured by SQUID magnetometer. YBa2(Cu1-xFex)3Oy was slowly cooled from 890°C in air, and a part of the samples was heated at 800°C in N2 gas. All products including those heated in N2 gas were annealed below 400°C in O2 gas. The measurements by SQUID were done at 5K and in magnetic fields up to 1T. Δ M, the difference in the hysteretic magnetization between the increasing and decreasing magnetic fields, of the samples prepared by heating in N2 gas followed by annealing in O2 gas shows the maximum value at x=0.02. This seems to indicate that the clustering of Fe atoms in the Cu1-O planes of the sample acts as effective pinning centers for flux lines.
