Temperature dependence of Mn1.56Co0.96Ni0.48O4 thin films optical properties by spectroscopic ellipsometry

• Optical properties under different temperature conditions are firstly reported.
• Three-phase model was built to fit ellipsometry parameters by TL dispersion function.
• The mechanism in variations of n and k has been investigated.

The optical properties of spinel Mn1.56Co0.96Ni0.48O4 thin films have been investigated by spectroscopic ellipsometry in the temperature range from 20 to 260 °C. By fitting the measured ellipsometric parameter data with a three-layer model by Tauc–Lorentz oscillator dispersion formula, the refractive index and extinction coefficient of the thin films are determined in the spectral range of 280–850 nm. The refractive index decreases in the short-wavelength region but increases in the long-wavelength region with increasing temperature. The extinction coefficient increases with increasing temperature in all visible region.