Flux pinning enhancement by twin boundaries

Abstract
The authors have measured the magnetization of single crystal YBa2Cu3O7- delta with all the twin planes orientated in only one direction. By rotating the magnetic field in the (ab)-plane, they find significant enhancements of the magnetization (up to a factor of 4.6), when the field is directed parallel to the twin boundaries. No angular dependence of the magnetization in the (ab)-plane could be detected at temperatures exceeding approximately=40 K.