Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T56: Cooperative Phenomena (Spin Structures, Spin Waves, Phase Transitions) II
11:30 AM–2:30 PM,
Thursday, March 9, 2023
Room: Room 304
Sponsoring
Unit:
GMAG
Chair: Travis Williams, Oak Ridge National Laboratory
Abstract: T56.00012 : Driven Hubbard model on a triangular lattice: Tunable Heisenberg antiferromagnetwith a chiral three-spin term
1:42 PM–1:54 PM
Presenter:
Diptiman Sen
(Indian Institute of Science Bangalore)
Author:
Diptiman Sen
(Indian Institute of Science Bangalore)
lattice. The electric field is incorporated through the phase of the nearest-neighbor hopping amplitude via the
Peierls prescription. When the on-site interaction is much larger than the hopping, the effective Hamiltonian
H_eff describing the spin sector can be found using a Floquet perturbation theory. To third order in the hopping,
H_eff is found to have the form of a Heisenberg antiferromagnet with three different nearest-neighbor couplings
(J_alpha, J_beta, J_gamma) on bonds lying along the different directions. Remarkably, when the periodic driving
breaks time-reversal symmetry, H_eff 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. The four parameters
(J_alpha, J_beta, J_gamma, 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 ground state
phase diagram 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 a triangular lattice can lead to an effective spin
model whose couplings can be tuned over a range of values thus producing a variety of interesting phases.
Reference:
S. Sur, A. Udupa and D. Sen, Phys. Rev. B 105, 054423 (2022).
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