paper

Spin waves and three-dimensionality in the high-pressure antiferromagnetic phase of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$

arXiv:2406.17546 · doi:10.1103/PhysRevLett.133.246702

Abstract

Quantum magnetic materials can provide explicit realizations of paradigm models in quantum many-body physics. In this context, SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ is a faithful realization of the Shastry-Sutherland model (SSM) for ideally frustrated spin dimers, even displaying several of its quantum magnetic phases as a function of pressure. We perform inelastic neutron scattering (INS) measurements on SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ at 5.5 GPa and 4.5 K, observing spin waves that characterize the high-pressure antiferromagnetic phase. The experimental spectra are well described by linear spin-wave calculations on a SSM with an inter-layer interaction, which is determined accurately as $J_{c} = 0.053 (3)$ meV. The presence of $J_{c}$ indicates the need to account for the three-dimensional nature of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$ in theoretical models, also at lower pressures. We find that the ratio between in-plane interactions, $J^{'} / J = 1.8 (2)$ , undergoes a dramatic change compared to lower pressures that we deduce is driven by a sharp drop in the dimer coupling, $J$ . Our results underline the wide horizons opened by high-pressure INS experiments on quantum magnetic materials.

Main text + supplemental material

Spin waves and three-dimensionality in the high-pressure antiferromagnetic phase of SrCu2​(BO3​)2​

Abstract

Spin waves and three-dimensionality in the high-pressure antiferromagnetic phase of SrCu $_{2}$ (BO $_{3}$ ) $_{2}$