Figure 3: A Fano resonance of the 24 meV phonon mode and magnetic specific heat.
(a) Fit of 24 meV phonon to a Fano profile after subtracting a temperature-dependent magnetic background. The 21 meV phonon on a low-energy side of the Fano resonance is fitted together with a Lorentzian profile. The inset depicts a schematic representation of eigenvector of the 24 meV Ag symmetry mode. The amplitude of the vibrations is represented by the arrow length. Golden balls indicate Ir ions and red balls are O ions. The Li atoms are omitted for simplicity. (b) Temperature dependence of the Fano asymmetry 1/|q| plotted together with the two-fermion form (1−f(ω))2 (solid line). (c) The energy ω and linewidth Γ as a function of temperature. The solid lines are a fit to an anharmonic phonon model. (d) Temperature dependence of the magnetic specific heat Cm derived from the Raman conductivity χ′′(ω)/ω.
