Projected wavefunction study of Spin-1/2 Heisenberg model on the Kagome lattice

TL;DR

This study uses Gutzwiller projected wavefunctions to analyze the spin-1/2 Heisenberg model on the Kagome lattice, identifying a U(1)-Dirac spin-liquid state as the lowest energy configuration, consistent with experimental observations.

Contribution

It demonstrates that the U(1)-Dirac spin-liquid state has the lowest energy and closely matches exact diagonalization results, providing insight into the quantum phase of the Kagome lattice model.

Findings

U(1)-Dirac spin-liquid state has the lowest energy

Energy closely matches that from exact diagonalization

U(1)-Dirac state describes a quantum phase with Dirac fermions

Abstract

We perform a Gutzwiller projected wavefunction study for the spin-1/2 Heisenberg model on the Kagome lattice to compare energies of several spin-liquid states. The result indicates that a U(1)-Dirac spin-liquid state has the lowest energy. Furthermore, even without variational parameters, the energy turns out to be very close to that found by exact diagonalization. We show that such a U(1)-Dirac state represents a quantum phase whose low energy physics is governed by four flavors of two-component Dirac fermions coupled to a U(1) gauge field. These results are discussed in the context of recent experiments on ZnCu$_3$(OH)$_6$Cl$_2$.