Multitude of Topological Phase Transitions in Bipartite Lattices with Interacting Electrons and Rashba Coupling

We performed a Hartree-Fock study on interacting electrons moving in two different bipartite lattices: the dice and the Lieb lattices, at half filling. The non-interacting part for both these lattices comprises of : a nearest-neighbour (NN) hopping term, a NN Rashba spin-orbit coupling term, and an onsite energy term. Both lattices develop ferrimagnetic order in the U-λ phase diagram, where U is the Hubbard onsite repulsion and λ the Rashba spin-orbit coupling strength. Along with this, we observed an unexpected multitude of topological phases for both these lattices. All these topological phases are ferrimagnetic, but they differ among themselves in their set of six Chern numbers. The Chern numbers |C| observed in our study ranges from 0 to 3, showing that large Chern numbers can be obtained by the effect of electronic correlations, adding to the recently discussed methodologies to increase |C| based on extending the hopping range in tight-binding models, using sudden quenches, or photonic crystals, all without including electronic interactions.

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[2] R. Soni, AB Sanyal, N. Kaushal, S. Okamoto, A. Moreo, E. Dagotto, arXiv.2110.03813 (2021)