  In this study, we explore the Josephson current-phase relation within a
planar diffuse tunneling superconducting multilayer junction subjected to a
parallel magnetic field. Our investigation involves computing the supercurrent
associated with a fixed jump in the phase of the order parameter at each of the
two insulating interfaces, allowing us to derive the current-phase relation for
the junction. Employing perturbation theory in junction conductance, we
determine both the first and second harmonics of the current-phase relation
under specific magnetic field conditions. Notably, the presence of a strong
spin-orbit interaction in the middle region of the junction introduces an
anomalous Josephson effect. The interplay between spin-orbit and Zeeman
interactions results in the emergence of an effective vector potential. This
specific characteristic induces a phase shift in each harmonic of the
current-phase relation without altering the overall shape of the relation. The
mechanism for the Josephson diode effect is discussed for disordered junctions
of multiband superconductors.
