Phases and magnetization process of an anisotropic Shastry-Sutherland model

TL;DR

This paper investigates the ground states and magnetization behavior of an anisotropic Shastry-Sutherland model, revealing quantum phase transitions, dimerized phases, and magnetization plateaus through Monte Carlo simulations and perturbation theory.

Contribution

It introduces a detailed analysis of the quantum phases and magnetization plateaus in an anisotropic Shastry-Sutherland model, highlighting the existence of specific crystalline patterns and phase boundaries.

Findings

Identification of a dimerized triplet phase separated from Neel order.

Observation of a persistent 1/3 magnetization plateau down to the Ising limit.

Discovery of a 1/2 magnetization plateau unique to the quantum regime.

Abstract

We examine ground state properties of the spin-1/2 easy-axis Heisenberg model on the Shastry-Sutherland lattice with ferromagnetic transverse spin exchange using quantum Monte Carlo and degenerate perturbation theory. For vanishing transverse exchange, the model reduces to an antiferromagnetic Ising model that besides Neel order harbors regions of extensive ground state degeneracy. In the quantum regime, we find a dimerized phase of triplet states, separated from the Neel ordered phase by a superfluid. The quantum phase transitions between these phases are characterized. The magnetization process shows a magnetization plateau at 1/3 of the saturation value, that persists down to the Ising limit, and a further plateau at 1/2 only in the quantum regime. For both plateaus, we determine the crystalline patterns of the localized triplet excitations. No further plateaus nor supersolid phases are found in this model.