Rectification from band gap oscillation

Abstract

We study a one-dimensional chain of identical atoms with two electronic orbitals and two electrons per atom, subject to an external oscillating pressure that periodically modulates the lattice spacing. This leads to time-dependent intra- and inter-orbital hopping amplitudes. In the tight-binding limit with weak inter-orbital hopping, the system exhibits two electronic bands separated by an oscillating indirect band-gap. By tuning hopping amplitudes and orbital energies, a periodic metal-insulator transition emerges in the half-filled system. When the frequency of this transition matches that of an external alternating electric field, the system undergoes half-wave rectification: it behaves as a conductor during one half-cycle and as an insulator during the other. This dynamic switching enables directional current flow and remains robust under small to intermediate onsite electron-electron interactions.