Fraunhofer oscillations in a multilayer system with Josephson coupling of layers

The equations for gauge-invariant phases are obtained for superconductors with Josephson coupling of the layers. Using these equations, we find the condition under which Fraunhofer oscillatory dependence of the critical current on parallel magnetic field H can be observed in such compounds: The width of the sample along the ab plane in the direction perpendicular to H should be smaller than the Josephson length ${\lambda }_{\mathit{J}}$=${\gamma }_{\mathit{s}}$, where γ is the penetration depth anisotropy ratio and s is the interlayer spacing. We show that in the presence of weak disorder such oscillations are more pronounced in a multilayer system than in a single Josephson junction with the same level of disorder. We present the expression for the c-axis critical density that is inherent to the intrinsic interlayer Josephson effect.