Vortex pinning regimes in YBa₂Cu₃O7−xbulk boundaries investigated by quantitative magnetic Hall microscopy

Magnetic Hall probe microscopy in combination with an inverse problem solver was used to simultaneously determine the intragranular and intergranular critical current density dependences on the applied field of YBCO melt-textured welds with [001]-misorientation angles from 0° to 30°. This methodology enabled us to investigate the pinning mechanisms of grain boundary vortices, which evolve from Abrikosov vortices (AVs) to Abrikosov–Josephson vortices (AJVs) and then to Josephson vortices (JVs) as the angle increases. We present a magnetic field versus grain boundary angle phase diagram at 77 K in which different intergrain vortex motion regimes can be identified.