LAUSR.org creates dashboard-style pages of related content for over 1.5 million academic articles. Sign Up to like articles & get recommendations!

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

Photo from wikipedia

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… Click to show full abstract

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 (Jα, Jβ , Jγ) on bonds lying along the different directions. Remarkably, when the periodic driving does not have time-reversal symmetry (TRS), Heff is also found to have a chiral three-spin interaction in each triangle, with the coefficient C of the interaction having opposite signs on upand down-pointing triangles. Thus periodic driving which breaks TRS 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 (Jα, Jβ , Jγ , 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 (colinear 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.

Keywords: hubbard model; model; triangular lattice; heisenberg antiferromagnet; chiral three; three spin

Journal Title: Physical Review B
Year Published: 2022

Link to full text (if available)


Share on Social Media:                               Sign Up to like & get
recommendations!

Related content

More Information              News              Social Media              Video              Recommended



                Click one of the above tabs to view related content.