The problem of control of the state and critical cur rent of Josephson junctions is of primary importance for creating superconducting electronic devices based on these junctions. As is known, the properties of Josephson junctions change noticeably in the presence of structural inhomogeneities in the junction region [1, 2]. The nonuniform distribution of the critical Josephson current density jc, which is due to the defects of the barrier, is responsible for a significant change in both the Fraunhofer pattern (dependence of the critical current of the junction Ic on the external magnetic field H) and the current–voltage character istic of the junction. For a typical experimental imple mentation, a periodic change in the thickness of the tunnel barrier of a long Josephson junction is accom panied by the appearance of additional peaks on the Ic (H) dependence and additional steps on the cur rent–voltage characteristic [3–5]. These features are observed at multiple values of the external field H when the spatial periods of the chain of Josephson vor tices and the lattice of artificial inhomogeneities become commensurate.

Josephson junctions, where the nonuniform distri bution of the Josephson phase difference appears owing to various features of tunneling through the bar rier, have been actively studied in recent years. In par ticular, because of the d symmetry of the supercon ducting order parameter and the microstructure of the junction, the Josephson junction at the interface between YBCO/Nb films is a sequence of alternating 0 and π microjunctions where the phase shifts between electrodes in the ground state are 0 and π, respectively (see [6, 7] and review [8]). A similar periodic structure consisting of short 0 and π Josephson junctions can be implemented in the superconductor–ferromagnet–