• Zager, Benjamin
• Bahrami, Faranak
• Kim, J.
• Haskel, Daniel
• Upton, M. H.

Abstract

<jats:title>Abstract</jats:title><jats:p>Understanding the interplay between the inherent disorder and the correlated fluctuating-spin ground state is a key element in the search for quantum spin liquids. H<jats:sub>3</jats:sub>LiIr<jats:sub>2</jats:sub>O<jats:sub>6</jats:sub> is considered to be a spin liquid that is proximate to the Kitaev-limit quantum spin liquid. Its ground state shows no magnetic order or spin freezing as expected for the spin liquid state. However, hydrogen zero-point motion and stacking faults are known to be present. The resulting bond disorder has been invoked to explain the existence of unexpected low-energy spin excitations, although data interpretation remains challenging. Here, we use resonant X-ray spectroscopies to map the collective excitations in H<jats:sub>3</jats:sub>LiIr<jats:sub>2</jats:sub>O<jats:sub>6</jats:sub> and characterize its magnetic state. In the low-temperature correlated state, we reveal a broad bandwidth of magnetic excitations. The central energy and the high-energy tail of the continuum are consistent with expectations for dominant ferromagnetic Kitaev interactions between dynamically fluctuating spins. Furthermore, the absence of a momentum dependence to these excitations are consistent with disorder-induced broken translational invariance. Our low-energy data and the energy and width of the crystal field excitations support an interpretation of H<jats:sub>3</jats:sub>LiIr<jats:sub>2</jats:sub>O<jats:sub>6</jats:sub> as a disordered topological spin liquid in close proximity to bond-disordered versions of the Kitaev quantum spin liquid.</jats:p>

Topics

• impedance spectroscopy
• Hydrogen
• stacking fault