Four-Spin Terms and the Origin of the Chiral Spin Liquid in Mott Insulators on the Triangular Lattice

Tessa Cookmeyer; Johannes Motruk; Joel E Moore

doi:10.1103/PhysRevLett.127.087201

Four-Spin Terms and the Origin of the Chiral Spin Liquid in Mott Insulators on the Triangular Lattice

Phys Rev Lett. 2021 Aug 20;127(8):087201. doi: 10.1103/PhysRevLett.127.087201.

Authors

Tessa Cookmeyer^{1

2}, Johannes Motruk^{1

2

3}, Joel E Moore^{1

2}

Affiliations

¹ Department of Physics, University of California, Berkeley, California 94720, USA.
² Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
³ Department of Theoretical Physics, University of Geneva, Quai Ernest-Ansermet 30, 1205 Geneva, Switzerland.

PMID: 34477420
DOI: 10.1103/PhysRevLett.127.087201

Abstract

At strong repulsion, the triangular-lattice Hubbard model is described by s=1/2 spins with nearest-neighbor antiferromagnetic Heisenberg interactions and exhibits conventional 120° order. Using the infinite density matrix renormalization group and exact diagonalization, we study the effect of the additional four-spin interactions naturally generated from the underlying Mott-insulator physics of electrons as the repulsion decreases. Although these interactions have historically been connected with a gapless ground state with emergent spinon Fermi surface, we find that, at physically relevant parameters, they stabilize a chiral spin liquid (CSL) of Kalmeyer-Laughlin (KL) type, clarifying observations in recent studies of the Hubbard model. We then present a self-consistent solution based on a mean-field rewriting of the interaction to obtain a Hamiltonian with similarities to the parent Hamiltonian of the KL state, providing a physical understanding for the origin of the CSL.