Resonating valence bond wave function for the two dimensional fractional spin liquid

TL;DR

This paper introduces a resonating valence bond wave function to model two-dimensional fractional spin liquids, accurately capturing low-energy excitations and incommensurate spin correlations observed in experiments.

Contribution

It proposes a novel projected BCS wave function as an effective ansatz for describing fractionalized spin-1/2 excitations in two-dimensional spin liquids.

Findings

Wave function reproduces neutron scattering dispersion relations.

Accurately models incommensurate spin correlations.

Effective for both 1D and 2D spin-1/2 systems.

Abstract

The unconventional low-lying spin excitations, recently observed in neutron scattering experiments on ${\rm Cs_2 Cu Cl_4}$, are explained with a spin liquid wave function. The dispersion relation as well as the wave vector of the incommensurate spin correlations are well reproduced within a projected BCS wave function with gapless and fractionalized spin-1/2 excitations around the nodes of the BCS gap function. The proposed wave function is shown to be very accurate for one-dimensional spin-1/2 systems, and remains similarly accurate in the two-dimensional model corresponding to ${\rm Cs_2 Cu Cl_4}$, thus representing a good ansatz for describing spin fractionalization in two dimensions.