“Elastic” and “inelastic” twins and pinning of magnetic flux lines (vortices) in single crystals YBa2Cu3O7–x

In this work, we studied the fixation of magnetic vortices (pinning effect) on “inelastic” and “elastic” twins, whose wedge-shaped peaks in the direction of twinning do not reach the crystal surface. The effectiveness of the “elastic” twins effect as pinning centers was studied by measuring of the critical transport current Jc in single crystals YBa2Cu3O7–x. The presented experimental data indicate that the “elastic” twins boundaries are effective pinning centers of the magnetic flux lines in single crystals of the compound under study. The main pinning centers of the vortices are dislocation clusters forming at the vertices of the “elastic” twins. The dislocation lines are located in the twin plane and, if the orientation of the magnetic vortices and dislocation lines coincide, the energy of the vortices decreases, the pinning force appears, fixing their location, which ultimately leads to an increase in the critical density of the transport electric current.