Coupling-induced emergent topology in a two-leg fermionic ladder
Phys. Rev. B 114, 115121 – Published 19 August, 2026
DOI: https://doi.org/10.1103/g3zb-4j2p
Abstract
We investigate the ground-state properties of spinless fermions on a two-leg ladder by allowing the nearest-neighbor hopping dimerization in one leg and uniform hopping in the other. In the noninteracting limit, we find that at half filling, the system exhibits robust topological behavior if the interleg hopping is allowed. Though depending on the dimerization pattern, the dimerized leg can be either topological or trivial in nature; here we show that by connecting such a leg to a uniform leg through interchain coupling, the overall system becomes topological irrespective of the dimerization pattern in the dimerized leg. As a result, a topological phase transition occurs as a function of the interleg hopping. When the interleg interaction is turned on, the topological phase survives and we obtain an interaction-induced topological phase transition. Finally, we reveal that when uniform interactions are included on all the bonds of the ladder, the topological phase transitions to a symmetry-broken charge-density wave (CDW) phase.
