Numerical Study of Excited States in the Shastry-Sutherland Model

TL;DR

This paper uses a variational approach to study excited states in the Shastry-Sutherland model, revealing phase boundaries and estimating coupling constants relevant to SrCu2(BO3)2.

Contribution

It introduces a variational method for excited states and provides new insights into phase transitions and coupling parameters in the model.

Findings

Helical order phase exists between singlet dimer and magnetic phases.

Estimated intra-dimer coupling J and inter-dimer coupling J' for SrCu2(BO3)2.

Energy differences align with perturbative calculations.

Abstract

We investigate excited states of the Shastry-Sutherland model using a kind of variational method. Starting from various trial states which include one or two triplet dimers, we numerically pursue the best evaluation of the energy for each set of quantum numbers. We present the energy difference as a function of either the coupling ratio or the momentum and compare them with the perturbative calculations. Our data suggest that the helical order phase exists between the singlet dimer phase and the magnetically ordered phase. In comparison with the experimental data we can estimate the intra-dimer coupling J and the inter-dimer coupling J' for SrCu2(BO3)2 : J'/J =0.65 and J = 87K.