Quantum Criticality and Spin Liquid Phase in the Shastry-Sutherland model

TL;DR

This paper uses advanced numerical methods to identify a narrow quantum spin liquid phase in the Shastry-Sutherland model, linking it to experimental observations and a unified quantum phase diagram.

Contribution

It demonstrates the existence of a spin liquid phase in the Shastry-Sutherland model using density-matrix renormalization group techniques, providing new insights into quantum criticality and phase transitions.

Findings

Identification of a narrow spin liquid phase between known states

Finite-size scaling supports the phase's existence

Experimental heat capacity data aligns with the theoretical spin liquid evidence

Abstract

Using the density-matrix renormalization group method for the ground state and excitations of the Shastry- Sutherland spin model, we demonstrate the existence of a narrow quantum spin liquid phase between the previously known plaquette-singlet and antiferromagnetic states. Our conclusions are based on finite-size scaling of excited level crossings and order parameters. Together with previous results on candidate models for deconfined quantum criticality and spin liquid phases, our results point to a unified quantum phase diagram where the deconfined quantum-critical point separates a line of first-order transitions and a gapless spin liquid phase. The frustrated Shastry-Sutherland model is close to the critical point but slightly inside the spin liquid phase, while previously studied unfrustrated models cross the first-order line. We also argue that recent heat capacity measurements in SrCu2(BO3)2 show evidence of the proposed spin liquid at pressures between 2.6 and 3 GPa.