Optimized RVB states of the 2-d antiferromagnet: Ground state and excitation spectrum

TL;DR

This paper presents an optimized resonating valence bond (RVB) state for the 2D antiferromagnetic spin-1/2 model, providing ground state energy, magnetization, and excitation spectrum insights.

Contribution

It introduces a parameter-free RVB ground state derived from Gutzwiller projection of Schwinger-boson mean-field solutions, with detailed spectral analysis.

Findings

Ground state energy of -0.6688J per site

Staggered magnetization of 0.311

Linear, gapless excitation spectrum near zero momentum

Abstract

The Gutzwiller projection of the Schwinger-boson mean-field solution of the 2-d spin-1/2 antiferromagnet in a square lattice is shown to produce the optimized, parameter-free RVB ground state. We get $-0.6688J$/site and $0.311$ for the energy and the staggered magnetization. The spectrum of the excited states is found to be linear and gapless near $\bk\cong 0$. Our calculation suggests, upon breaking of the rotational symmetry, $\epsilon_{\bk}\cong 2JZ_{r} \sqrt{1-\gamma_{\bk}^{2}}$ with $Z_{r}\cong 1.23$. To appear in Phys. Lett. A (1993).