Splitting rules of electronic miniband in Fibonacci superlattices: a gap map approach

The splitting rules of fragmental miniband in Fibonacci superlattices (FSLs) with arbitrary basis and generation orders are presented through a gap map diagram. Based on the gap map, we find the invariant conditions of the band structure splitting in the FSL for arbitrary generation orders. Moreover, the band structure splitting can be divided to form many regions, each having a similar pattern. In each region, the widths of most gap bands except two major gaps will decrease for increasing the generation order. It is interesting that the center and gap width of the major gaps will converge to constant values for increasing the generation order of the FSL. Based on the splitting rules displayed in the gap map, it is convenient to predict the fragmental band structure in the FSL for arbitrary generation orders and bases.