New valence bond crystal phase of a frustrated spin-1/2 square lattice antiferromagnet

TL;DR

This paper introduces a novel magnetically disordered ground state in a frustrated spin-1/2 square lattice antiferromagnet, characterized by a valence bond crystal of four-spin plaquettes, supported by theoretical and numerical evidence.

Contribution

It proposes a new valence bond crystal phase for frustrated quantum antiferromagnets, showing it is energetically favorable over previous states using perturbation and bond-operator methods.

Findings

The new phase has lower energy than the columnar dimer state.

Numerical data supports realization of this phase at intermediate frustration.

The phase is an array of spin singlets on four-spin plaquettes.

Abstract

We propose a new type of magnetically disordered ground state for a frustrated quantum antiferromagnet. This disordered state is an array of spin singlets spontaneously formed on four spin plaquettes. Both perturbation results and bond-operator calculations show that this phase has lower energy than the columnar dimer state. Analysis of available numerical data on finite clusters also supports the conclusion that this state is realized at intermediate frustrations.