Freezing of a Disorder Induced Spin Liquid with Strong Quantum Fluctuations
Xiao Hu, Daniel M. Pajerowski, Depei Zhang, A. Podlesnyak, Yiming Qiu, Qing Huang, Haidong Zhou, Israel Klich, А. И. Колесников, M. B. Stone, Seung-Hun Lee
Abstract
${\mathrm{Sr}}_{2}{\mathrm{CuTe}}_{0.5}{\mathrm{W}}_{0.5}{\mathrm{O}}_{6}$ is a square-lattice magnet with superexchange between $S=\frac{1}{2}{\mathrm{Cu}}^{2+}$ spins mediated by randomly distributed Te and W ions. Here, using sub-K temperature and $20\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ energy resolution neutron scattering experiments we show that this system transits from a gapless disorder-induced spin liquid to a new quantum state below ${\mathbit{T}}_{\mathbit{f}}=1.7(1)\text{ }\text{ }\mathrm{K}$, exhibiting a weak frozen moment of $⟨\mathbit{S}⟩/\mathbit{S}\ensuremath{\sim}0.1$ and low energy dynamic susceptibility, ${\mathbit{\ensuremath{\chi}}}^{\ensuremath{'}\ensuremath{'}}(\ensuremath{\hbar}\mathbit{\ensuremath{\omega}})$, linear in energy which is surprising for such a weak freezing in this highly fluctuating quantum regime.