DMRG Numerical Study of the Kagom\'{e} Antiferromagnet

TL;DR

This study uses DMRG to analyze the kagome antiferromagnet, revealing a gapped spin liquid with specific magnetic properties and confirming the presence of gapless singlet excitations.

Contribution

First numerical DMRG analysis of the kagome antiferromagnet revealing a gapped spin liquid with detailed excitation spectrum.

Findings

Ground state is a magnetically disordered spin liquid.

Spin triplet excitation gap is approximately 0.055.

Presence of gapless singlet excitations confirmed.

Abstract

We numerically study the spin-1/2 antiferromagnetic Heisenberg model on the kagom\'{e} lattice using the density-matrix renormalization group (DMRG) method. We find that the ground state is a magnetically disordered spin liquid, characterized by an exponential decay of spin-spin correlation function in real space and a magnetic structure factor showing system-size independent peaks at commersurate antiferromangetic wavevectors. We obtain a spin triplet excitation gap $\Delta E(S=1)=0.055\pm 0.005$ by extrapolation based on the large size results, and confirm the presence of gapless singlet excitations. The physical nature of such an exotic spin liquid is also discussed.