Absolutely continuous energy bands in the electronic spectrum of quasiperiodic ladder networks

• Electronic spectrum of aperiodic ladder networks is investigated within tight-binding framework.
• A certain relationship between the parameters of the Hamiltonian describing the system triggers absolutely continuous energy bands in the electronic spectrum.
• A possibility of re-entrant metal–insulator transition opens up as the number of strands of ladder network increases in the transverse direction.
• A two-terminal charge transport for a finite size network is computed.

The energy spectra of quasi-one-dimensional quasiperiodic ladder networks are analyzed within a tight binding description. In particular, we show that if a selected set of sites in each strand of a ladder is tunnel-coupled to quantum dots attached from a side, absolutely continuous subbands can be generated in the spectrum if one tunes the dot potential and the dot-strand coupling appropriately. Typical cases with two and three strand Fibonacci ladders in the off-diagonal model are discussed in details. We also discuss the possibility of re-entrant insulator–metal transition for a general n-strand ladder network when n becomes large. The observations remain valid even in the case of a disordered ladder network with the same constituents. The results are analytically exact.

A method of engineering absolutely continuous energy bands in the electronic spectrum of multi-strand aperiodic ladder networks is revealed. Figure optionsDownload as PowerPoint slide