Circular current in a one-dimensional Hubbard quasi-periodic Su-Schrieffer-Heeger ring.

In this work, we investigate the behavior of interacting electrons in a Su-Schrieffer-Heeger (SSH) quantum ring, threaded by an  Aharonov-Bohm (AB) flux $\phi$, within a tight-binding (TB) framework. The site energies of the ring follow the Aubry-Andre-Harper (AAH) pattern, and, depending on the specific arrangement of neighboring site energies two different configurations, namely, non-staggered and staggered, are taken into account. The electron-electron (e-e) interaction is incorporated through the well-known Hubbard form and the results are computed within the mean-field (MF) approximation. Due to AB flux $\phi$, a non-decaying charge current is established in the ring, and its characteristics are critically studied in terms of the Hubbard interaction, AAH modulation, and hopping dimerization. Several unusual phenomena are observed under different input conditions, that might be useful to analyze the properties of interacting electrons in similar kinds of other fascinating quasi-crystals in the presence of additional correlation in hopping integrals. A comparison between exact and mean-field results is given, for the sake of completeness of our analysis.