Raman scattering experiment

A polarized, resolved Raman spectroscopy was employed to detect spin and phonon excitations of single crystals of β- and γ-Li₂IrO₃. Raman scattering experiments were performed in backscattering geometry with the excitation line λ=532.1 nm of a Nd:YAG (neodymium-doped yttrium aluminium garnet) solid-state laser. The scattered spectra were collected using a micro-Raman spectrometer (Jobin Yvon LabRam) equipped with a liquid-nitrogen-cooled charge-coupled device. A notch filter and a dielectric edge filter were used to reject Rayleigh scattering to a lower cutoff frequency of 60 cm⁻¹. The laser beam was focused to a few-micrometre-diameter spot on the surface of the crystal using a × 50 magnification microscope objective. The samples were mounted onto a liquid-He-cooled continuous flow cryostat, while varying a temperature between 6 and 300 K. All Raman spectra were corrected for heating.