Anomalous persistent current in a 1D dimerized ring with aperiodic site potential: Non-interacting and interacting cases

Abstract

In this work, we investigate the magnetic response by examining flux-driven circular currents in a Su–Schrieffer–Heeger (SSH) tight-binding (TB) ring threaded by an Aharonov–Bohm (AB) flux, $\varphi$. We consider both non-interacting and interacting electrons, where site energies are modulated by a slowly varying cosine form. Repulsive electron–electron interaction is incorporated through an on-site Hubbard term, and we analyze the system using the Hartree–Fock (HF) mean-field (MF) approximation. We discuss the characteristics of flux-driven circular currents to aperiodic potentials, dimerized hopping integrals, and Hubbard interactions. For the chosen aperiodic potential, both the strength and configuration play a crucial role, and we explore these aspects in depth. Interestingly, we observe a counterintuitive delocalizing effect as the aperiodic potential increases, unlike in conventional disordered rings. The effects of system size, filling factor, the presence of circular spin current, and the accuracy of MF results are also discussed. Finally, we provide a brief description of possible experimental realizations of our chosen quantum system. This investigation can be extended to explore additional properties in various loop substructures, promising further insights.