The mixed state of superlattice of superconducting sheets

The author has investigated the mixed state of a superlattice of superconducting sheets, which is a model for the cuprate superconductor and the superlattices made from them. He has also studied the relevant length scales. It is shown that only when the separation between the sheets l is larger than lambda _eff= lambda ²/d can the system be viewed as a collection of separate sheets; here lambda _eff is the screening length for a single sheet. It is argued that there are two Abrikosov lattices; one is associated with the component of the field which is parallel to the sheets, while the second corresponds to the field component perpendicular to the sheets. It is shown that the two lattices interact and can form a commensurate structure with novel properties similar to those found experimentally.