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Driven Hubbard model on a triangular lattice: Tunable Heisenberg antiferromagnet with a chiral three-spin term

Sur, S and Udupa, A and Sen, D (2022) Driven Hubbard model on a triangular lattice: Tunable Heisenberg antiferromagnet with a chiral three-spin term. In: Physical Review B, 105 (5).

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Official URL: https://doi.org/10.1103/PhysRevB.105.054423


We study the effects of a periodically varying electric field on the Hubbard model at half filling on a triangular lattice. The electric field is incorporated through the phase of the nearest-neighbor hopping amplitude via the Peierls prescription. When the on-site interaction U is much larger than the hopping, the effective Hamiltonian Heff describing the spin sector can be found using a Floquet perturbation theory. To third order in the hopping, Heff is found to have the form of a Heisenberg antiferromagnet with three different nearest-neighbor couplings (Ja,J�,J?) on bonds lying along the different directions. Remarkably, when the periodic driving does not have time-reversal symmetry, Heff can also have a chiral three-spin interaction in each triangle, with the coefficient C of the interaction having opposite signs on up- and down-pointing triangles. Thus periodic driving which breaks time-reversal symmetry can simulate the effect of a perpendicular magnetic flux which is known to generate such a chiral term in the spin sector, even though our model does not have a magnetic flux. The four parameters (Ja,J�,J?,C) depend on the amplitude, frequency, and direction of the oscillating electric field. We then study the spin model as a function of these parameters using exact diagonalization and find a rich phase diagram of the ground state with seven different phases consisting of two kinds of ordered phases (collinear and coplanar) and disordered phases. Thus periodic driving of the Hubbard model on the triangular lattice can lead to an effective spin model whose couplings can be tuned over a range of values thereby producing a variety of interesting phases. © 2022 American Physical Society.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to authors
Keywords: Antiferromagnetic materials; Ground state; Hubbard model; Magnetic flux; Perturbation techniques, Half-filling; Heisenberg antiferromagnets; Hopping amplitude; Nearest neighbor hopping; Peierls; Site interaction; Spin models; Time reversal symmetries; Triangular-lattice; Tunables, Electric fields
Department/Centre: Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Division of Physical & Mathematical Sciences > Physics
Date Deposited: 12 May 2022 07:02
Last Modified: 12 May 2022 07:02
URI: https://eprints.iisc.ac.in/id/eprint/71639

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