Quantum spin liquid phase in the Shastry-Sutherland model revealed by high-precision infinite projected entangled-pair states

TL;DR

This study uses advanced tensor network simulations to identify a narrow quantum spin liquid phase in the Shastry-Sutherland model, clarifying its complex zero-field phase diagram.

Contribution

The paper introduces high-precision iPEPS simulations with improved optimization, revealing a previously uncertain quantum spin liquid phase in the model.

Findings

Discovery of a narrow quantum spin liquid phase between known magnetic phases.

Lower energy variational states than previous methods.

Systematic extrapolation to infinite bond dimension enhances accuracy.

Abstract

The Shastry-Sutherland model is an effective model of the layered material SrCu$_2$(BO$_3$)$_2$, which exhibits an extremely rich phase diagram as a function of pressure and magnetic field. Motivated by the recent controversy regarding its phase diagram at zero magnetic field, we perform large-scale simulations based on infinite projected entangled-pair states (iPEPS), a two-dimensional tensor network ansatz to represent the ground state directly in the thermodynamic limit. By employing the latest optimization techniques, we obtain variational states with lower energy than previous results obtained from other methods. Using systematic extrapolations to the exact infinite bond dimension limit, our simulations reveal a narrow quantum spin liquid phase between the plaquette and antiferromagnetic phases in the range $0.785(5) \le J'/J \le 0.82(1)$.