Ground state properties of two spin models with exactly known ground states on the square lattice

TL;DR

This paper introduces a new 2D spin model with an exactly known ground state, and uses variational and exact methods to analyze its critical properties and compare with the Shastry-Sutherland model.

Contribution

It presents a novel 2D spin model with an exactly known ground state and provides bounds for its critical coupling using variational and exact diagonalization methods.

Findings

Calculated bounds for the critical coupling of the new model.

Analyzed finite-size systems up to 6x6 for both models.

Compared properties of the new model with the Shastry-Sutherland model.

Abstract

We introduce a new two-dimensional model with diagonal four spin exchange and an exactly knownground-state. Using variational ansaetze and exact diagonalisation we calculate upper and lower bounds for the critical coupling of the model. Both for this model and for the Shastry-Sutherland model we study periodic systems up to system size 6x6.