Vortex lattice accommodation on twin boundaries in YBa2Cu3O7 studied by neutron diffraction

An extensive study of small angle neutron scattering was performed in twinn ed YBa2Cu3O7 crystals in its superconducting state as a function of the ang le theta(B) between the c-axis of the crystal and the magnetic field. The h alf of the twin boundaries are oriented in the horizontal plane, which also contains the neutron beam and the magnetic field. Two different diffractio n patterns are studied as a function of theta(B) at 5 Ii and B = 0.5 T, one along the c-axis of the crystal, the other one along the applied field. Th ese variations are interpreted in the model of accommodation of the vortice s on the twin planes by zigzagging from these planes to the ab-planes of th e crystal, in order to minimize their energy.