Effect of structural disorder on the Kitaev magnet Ag$_{3}$LiIr$_{2}$O$_{6}$

Abstract: Searching for an ideal Kitaev spin liquid candidate with anyonic excitations and long-range entanglement has motivated the synthesis of a new family of intercalated Kitaev magnets such as H${3}$LiIr${2}$O${6}$, Cu${2}$IrO${3}$, and Ag${3}$LiIr${2}$O${6}$. The absence of a susceptibility peak and a two-step release of the magnetic entropy in these materials has been proposed as evidence of proximity to the Kitaev spin liquid. Here we present a comparative study of the magnetic susceptibility, heat capacity, and muon spin relaxation ($\mu$SR) between two samples of Ag${3}$LiIr${2}$O${6}$ in the clean and disordered limits. In the disordered limit, the absence of a peak in either susceptibility or heat capacity and a weakly depolarizing $\mu$SR signal may suggest a proximate spin liquid ground state. In the clean limit, however, we resolve a peak in both susceptibility and heat capacity data, and observe clear oscillations in $\mu$SR that confirm long-range antiferromagnetic ordering. The $\mu$SR oscillations fit to a Bessel function, characteristic of an incommensurate order, as reported in the parent compound $\alpha$-Li${2}$IrO$_{3}$. Our results clarify the role of structural disorder in the intercalated Kitaev magnets.