A Candidate for the Quantum Spin Liquid Ground-State in the Shastry-Sutherland Lattice Material Yb$_2$Be$_2$GeO$_7$

TL;DR

This study identifies Yb$_2$Be$_2$GeO$_7$ as a promising candidate for a quantum spin liquid ground state within the Shastry-Sutherland lattice, based on experimental evidence of lack of magnetic order and persistent spin dynamics at very low temperatures.

Contribution

The paper reports the discovery of a new rare-earth material, Yb$_2$Be$_2$GeO$_7$, exhibiting properties consistent with a quantum spin liquid in the Shastry-Sutherland model.

Findings

Yb$_2$Be$_2$GeO$_7$ shows no magnetic order down to 17 mK.

Persistent spin dynamics observed in Yb$_2$Be$_2$GeO$_7$.

Yb$_2$Be$_2$GeO$_7$ is a candidate for quantum spin liquid ground state.

Abstract

The quasi-2D Shastry-Sutherland model has remained topical in the field of condensed matter physics for the last two decades, following the experimental realization of the model in the material SrCu$_2$(BO$_3$)$_2$. Since then, research into the Shastry-Sutherland system has revealed more nuanced physics than initially predicted; recent theoretical works have even predicted a quantum spin liquid phase may exist. Herein, we report on a new Shastry-Sutherland lattice material, Yb$_2$Be$_2$GeO$_7$, of the rare-earth melilite family RE$_2$Be$_2$GeO$_7$. We find, through SQUID magnetometry, powder neutron diffraction, specific heat capacity, and muon spin relaxation, that Yb$_2$Be$_2$GeO$_7$ lacks magnetic order and exhibits persistent spin dynamics to at least 17 mK. We propose the Shastry-Sutherland lattice material Yb$_2$Be$_2$GeO$_7$ as a candidate to host a quantum spin liquid ground-state.