Numerical study of incommensurability of the spiral state on spin-1/2 spatially anisotropic triangular antiferromagnets using entanglement renormalization

TL;DR

This study uses entanglement renormalization tensor networks to analyze the quantum ground states of anisotropic triangular antiferromagnets, revealing incommensurate spiral order influenced by quantum fluctuations.

Contribution

It introduces a tensor network variational method to accurately study incommensurate spiral states in anisotropic triangular antiferromagnets, extending understanding beyond classical predictions.

Findings

Incommensurate spiral magnetic order persists in the quantum ground state.

Quantum fluctuations weaken inter-chain coupling but do not destroy magnetic order.

Wave vectors match series expansion results, validating the method.

Abstract

The ground state of an S=1/2 antiferromagnetic Heisenberg model on a spatially anisotropic triangular lattice, which is an effective model of Mott insulators on a triangular layer of organic charge transfer salts or Cs2CuCl4, is numerically studied. We apply a numerical variational method by using a tensor network with entanglement renormalization, which improves the capability of describing a quantum state. Magnetic ground states are identified for 0.7 <= J2/J1 <= 1 in the thermodynamic limit, where J1 and J2 denote the inner-chain and inter-chain coupling constants, respectively. Except for the isotropic case (J1=J2), the magnetic structure is spiral with an incommensurate wave vector that is different from the classical one. The quantum fluctuation weakens the effective coupling between chains, but the magnetic order remains in the thermodynamic limit. In addition, the incommensurate wave number is in good agreement with that of the series expansion method.