Phonon damping by magnetic fluctuations in the magnetic spin-orbit insulator, Ba4Ir3O10*

The insulator spin chain compound Ba₃Ir₄O₁₀ is a new candidate for a frustrated quantum spin liquid, which was reported to have a stabilized quantum spin liquid state down to 0.2 K. The spin liquid is extraordinarily sensitive to small perturbations. The replacement of approximately 2% of barium with strontium or growth of the samples in the magnetic field readily lift the frustration parameter and this doped material has long-range order from an antiferromagnetic transition at 130 K. We will present results of Raman scattering experiments on Sr-doped, undoped and magnetic field-grown samples of Ba₃Ir₄O₁₀, which demonstrate damping of the phonons by magnetic fluctuations. The results will be interpreted in terms of magnon-phonon coupling due to strong spin-orbit interaction.