Quantum spin Hall insulator on the honeycomb lattice induced by ferromagnetic exchange interaction

Abstract

We study the many-body instabilities of correlated electrons on the half-filled honeycomb lattice with enhanced exchange coupling. The system is described by an extended Hubbard model including the next-nearest-neighbor Coulomb repulsion ($V_2$) and the nearest-neighbor exchange interaction ($J$). We use the truncated unity functional renormalization group approach to determine a schematic ground-state phase diagram with higher resolution in the parameter space of $V_2$ and $J$. In the absence of the on-site repulsion and presence of sizable next-nearest-neighbor repulsion and enhanced nearest-neighbor exchange interaction, we encounter the quantum spin Hall phase, the spin-Kekulé phase, and the three-sublattice and the incommensurate charge-density-wave phases. We propose a scheme for combining consistently the truncated unity functional renormalization group and the mean-field approximation, which is distinct from the conventional one that directly uses the renormalization-group results as an input for the mean-field calculation. This scheme is used to study in detail the quantum spin Hall phase, presenting some characteristics like the bulk gap, the Chern number and the helical edge states.

17 pages, 6 figures, 1 table

References in corpus (8)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Topological Mott Insulators
• Rydberg-Atom Quantum Simulation and Chern Number Characterization of a Topological Mott Insulator
• Charge instabilities and topological phases in the extended Hubbard model on the honeycomb lattice with enlarged unit cell
• Reference results for the momentum space functional renormalization group
• Antiferromagnetism and competing charge instabilities of electrons in strained graphene from Coulomb interactions
• TU${}^2$FRG -- a scalable approach for truncated unity functional renormalization group in generic fermionic models

Cited by in corpus (2)

• Consistent combination of truncated-unity functional renormalization group and mean-field theory
• Spin bond order driven by extended repulsive interactions in doped graphene