Pancake vortices in stacks of thin superconducting films or layers are considered. It is stressed that in the absence of Josephson coupling topological restrictions upon possible configurations of vortices are removed and various examples of structures forbidden in bulk superconductors are given. In particular, it is shown that vortices may skip surface layers in samples of less than a certain size $R_c$ which might be macroscopic. The Josephson coupling suppresses $R_c$ estimates.

• Received 21 June 1999

DOI:https://doi.org/10.1103/PhysRevB.61.1623