The spontaneous disorder according to flat bands

Abstract

Abstract A bosonic Creutz–Hubbard ladder is studied by solving the interacting Bose–Hubbard model, with the help of exact diagonalization method. Under certain parameters, a single-particle energy spectrum possessing two flat energy bands is obtained. Due to these flat bands, we identify the spontaneous disorder in the presence of interaction, which breaks the translational symmetry of lattice system. Out of flat bands and taking a flux quanta as π / 2 , the checkerboard phase associated with Meissner currents can be observed, as well as the regular biased ladder (BL) phase, which particularly presents a novel type of interlaced chiral current. We further figure out a modulated BL phase, whose imbalance on the occupancies between two legs is constant, whereas the density distribution on either leg oscillates periodically, followed by compound currents.