Effects of applied electrical field on electronic structures in LaNiO ₃ conductive metallic oxide film: An optical spectroscopic study

The reflectance spectra of LaNiO₃ film on silicon have been investigated in the wavelength range of 190-2650 nm (0.47-6.5 eV) under different external direct-current voltage. The Drude-Lorentz dispersion model is used to extract the optical function. The O 2p to Ni 3d electronic transition can be uniquely assigned to the energy of about 1.96 eV and decreases with decreasing applied voltage. The discrepancy from the real part of dielectric function with the applied voltage has a strong spectral dependence. The optical conductivity variation under different external voltage indicates that the electrical field can induce the modification of the carrier transport.