Mechanisms of the Effect of External and Internal Demagnetizing Fields on the Formation, Dynamics, and Evolution of a Vortex Structure in Twinned High-Temperature YBa₂Cu₃O_{7 – x} Superconductors

It is shown that large vortex molecules pinned at points of the intersection of periodic twin boundaries form first in twinned YBa₂Cu₃O_7 – x compounds. Low-mobility molecules of similar shape consist of intra-twin junction vortices and intertwin junction antivortices, between which Abrikosov and Josephson vortices trapped at the banks of twinning boundaries and within the latter are sandwiched, respectively. Strengthening the field enhances its interaction with the residual demagnetizing fields of twins and contributes to the decay of multicomponent vortex molecules into smaller ones with two components.