Tunnel Junctions with a Moire Superlattice as a Barrier

Recently, moire superlattices have attracted considerable attention because they are found to exhibit intriguing electronic phenomena of tunable Mott insulators and unconventional superconductivity. These phenomena are highly related to the physical mechanism of the interlayer coupling. However, up to now, there has not existed any theory that can completely interpret the experimental results of the interlayer conductance of moire superlattices. In order to solve this problem, the superposition of periods and the corresponding coherence, which are the essential characteristics of moire superlattices, should be considered more sufficiently. Therefore, it is quite necessary to introduce optical methods to study moire superlattices. Here, we develop a theory for moire superlattices, which are founded on traditional optical scattering theory. The theory can interpret both the continuously decreasing background and the peak of the interlayer conductance observed in the experiments with a unified mechanism. We show that the decreasing background of the interlayer conductance arises from the increasing strength of the interface potential and the peak roots from the scattering resonance of the interface potential. The present work is crucial for understanding the interlayer coupling of the moire superlattice and provides a solid theoretical foundation for the application of moire superlattices.