Confirming the high pressure phase diagram of the Shastry-Sutherland model

TL;DR

This study uses muon spin rotation to explore the magnetic phase diagram of SrCu2(BO3)2 under high pressure, confirming the absence of magnetic order and indicating a transition to a plaquette phase.

Contribution

It provides experimental evidence supporting the existence of a plaquette phase in the Shastry-Sutherland model material under high pressure.

Findings

No long-range magnetic order at high pressures

Changes in Cu spin fluctuations above 21 kbar

Support for a plaquette phase formation

Abstract

A Muon Spin Rotation ($\mu$+SR) study was conducted to investigate the magnetic properties of SrCu2(BO3)2 (SCBO) as a function of temperature/pressure. Measurements in zero field and transverse field confirm the absence of long range magnetic order at high pressures and low temperatures. These measurements suggest changes in the Cu spin fluctuations characteristics above 21 kbar, consistent with the formation of a plaquette phase as previously suggested by inelastic neutron scattering measurements. SCBO is the only known realisation of the Shatry-Sutherland model, thus the ground state mediating the dimer and antiferromagnetic phase is likekly to be a plaquette state.