Oxygen-Dependent Evolution and Scaling of Magnetic Anisotropy in REBa2Cu3O y Revealed by Orientation Fluctuation Analysis

Abstract

Magnetic-field-induced microcrystal alignment of REBa2Cu3Oy (RE123) superconductors is governed by magnetic susceptibility anisotropy, which depends strongly on oxygen content and twin-domain formation. In this study, the anisotropy of Y0.5Er0.5Ba2Cu3Oy (YEr123) and DyBa2Cu3Oy (Dy123) was quantitatively evaluated using orientation fluctuation analysis under a modulated rotating magnetic field. The easy and hard magnetic axes correspond to the b- and c-axes, respectively, in YEr123, and vice versa in Dy123. The results reveal that the normalized anisotropy exhibits a systematic oxygen-dependent evolution in the higher-oxygen orthorhombic region, and a scaling relationship is established between different RE systems through a constant multiplicative factor. This indicates that the oxygen-dependent variation of magnetic anisotropy follows a common functional form for the Dy123 and YEr123 systems examined in the present study and may be applicable to additional RE123 compounds. Deviations from the linear scaling behavior observed in the higher-oxygen orthorhombic region are identified at lower oxygen contents. Twin-corrected analysis shows that the observed anisotropy reflects a balance between intrinsic anisotropy enhanced by oxygen ordering and its reduction due to twin-domain averaging. These findings provide a unified framework for understanding magnetic anisotropy in RE123 systems and clarify the mechanism governing three-dimensional magnetic alignment.