Unconventional bipartite entanglement in the quantum dimer magnet Yb2Be2SiO7

TL;DR

The paper studies a quantum dimer magnet, Yb2Be2SiO7, and finds it hosts an unusual entangled state with a unique singlet ground state.

Contribution

The study reveals an unconventional bipartite entanglement in a quantum dimer magnet with strong spin-orbit coupling.

Findings

Yb2Be2SiO7 does not show magnetic order down to 50 mK.

The system's ground state is described by an anisotropic singlet wavefunction.

Strong spin-orbit coupling leads to unusual entangled states in quantum dimer magnets.

Abstract

The quantum dimer magnet, with antiferromagnetic intradimer and interdimer Heisenberg exchange between spin-1/2 moments, is known to host an \documentclass[12pt]{minimal}
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\begin{document}$$(\left|\uparrow \downarrow \right\rangle -\left|\downarrow \uparrow \right\rangle )/\sqrt{2}$$\end{document}(↑↓−↓↑)/2 singlet ground state when the intradimer exchange is dominant. Rare-earth-based quantum dimer systems with strong spin-orbit coupling offer the opportunity for tuning their magnetic properties by using magnetic anisotropy as a control knob. Here, we present bulk characterization and neutron scattering measurements of the quantum dimer magnet Yb2Be2SiO7. We find that the Yb3+ ions can be described by an effective spin-1/2 model at low temperatures and the system does not show signs of magnetic order down to 50 mK. The magnetization, heat capacity, and neutron spectroscopy data can be well-described by an isolated dimer model with highly anisotropic exchange that stabilizes a singlet ground state with a wavefunction \documentclass[12pt]{minimal}
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\begin{document}$$(\left|\uparrow \uparrow \right\rangle -\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$\end{document}(↑↑−↓↓)/2 or \documentclass[12pt]{minimal}
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\begin{document}$$(\left|\uparrow \uparrow \right\rangle+\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$\end{document}(↑↑+↓↓)/2. Our results show that strong spin-orbit coupling can induce unusual entangled states of matter in quantum dimer magnets.

The Shastry-Sutherland model consists of orthogonal dimers in a two dimensional plane, and has proved a rich basis for both theoretical and experimental investigation of quantum magnetism. Here, Brassington et al show that Yb2Be2SiO7 hosts an anisotropic variant of the Shastry Sutherland model.

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