Spin dynamics in the Dirac $U(1)$ spin liquid YbZn${}_2$GaO${}_5$

Abstract

YbZn${}_2$GaO${}_5$ is a promising candidate for realizing a quantum spin liquid (QSL) state, particularly owing to its lack of significant site disorder. Pulsed-field magnetometry at 0.5 K shows magnetization saturating near 15 T, with a corrected saturation moment of 2.1(1) $\hat{I}{¼}_{\mathrm{B}}$ after subtracting the van Vleck contribution. Our zero-field $\hat{I}¼$SR measurements down to milliKelvin temperatures provide evidence for a dynamic ground state and the absence of magnetic order. To probe fluctuations in the local magnetic field at the muon site, we performed longitudinal field $\hat{I}¼$SR experiments. These results provide evidence for spin dynamics with a field dependence that is consistent with a U1A01 Dirac QSL as a plausible description of the ground state.

7 pages, 7 figures