Observation of Non-Uniform Twin Microstructures in Dy123 Superconductor for Magnetic Biaxial Alignment

Despite the formation of twinned microstructures in grains of REBa
₂
Cu
₃
O
_y
with y ∼ 7, their grains can be biaxial aligned under modulated rotating magnetic fields (MRFs). In the present study, direct observation of twinned microstructures by transmission electron microscopy (TEM) was examined for a magnetically biaxial aligned grain of DyBa
₂
Cu
₃
O
_y
with y ∼ 7. Use of the biaxial aligned grain enabled us to obtain planar views by TEM easier from a technical viewpoint. Furthermore, an inhomogeneous abundance ratio of two different types of domains (domain ratio) was clarified from the planar view of the grain. The present study strongly suggested that triaxial magnetic anisotropy of RE123 was remained in the grain level due to the inhomogeneous domain ratio, and it led to the achievement of the biaxial alignment of RE123 grains under MRFs.