Magneto-Optical Observation of Flux Penetration in an a-axis Aligned Bi-2212 Superconductor

Magnetic flux penetration in an a-axis aligned Bi-2212 superconductor for fields perpendicular to the bc-plane are observed by a magneto-optical technique. Flux density in intragranular region is almost the same as the external field. On the other hand, flux barely penetrate along the low angle grain boundary, and flux density gradient is formed in the vicinity of it. The contribution of the low angle boundary to the magnetization is estimated by using a flux pinning model, and is compared with magnetization measurements.