Optical properties for the Mott transition in VO2

Abstract

The relationship between the first-order metal-insulator transition (MIT) and the structural phase transition (SPT) in VO2 film is analyzed by dielectric function, optical conductivity, plasma energy, and electrical conductivity. The MIT and SPT temperatures in VO2 films were approximately 68 and 75 °C, respectively, with an intermediate phase existing between 68 and 75 °C. The optical and electrical results indicate that the first-order MIT in VO2 films is not driven by the SPT

On the energy scale involved in the metal to insulator transition of quadruple perovskite EuCu3Fe4O12: infrared spectroscopy and ab-initio calculations

“…However, no clear plasma edge is observed. Such a behavior is often found in correlated transition metal oxides2122232425. As the temperature is decreased down to 250 K, the spectra do not show any qualitative change.…”

Core-shell VO2@TiO2 nanorods that combine thermochromic and photocatalytic properties for application as energy-saving smart coatings

“…The entire spectral range in question can be divided into two regions: at a shorter wavelength region A the transmittance at 90°C is higher than 25°C; and at a longer wavelength region B the transmittance at 25°C is much higher than that at 90°C (the so-called IR switching) In the region B, the Tr behaviour is very conventional for VO 2 , in which the Tr is lower at temperatures above the Tc (metallic R phase) than that at lower temperatures (semiconducting M1 phase). The plasma frequency (ω p ) for the R phase in polycrystalline thin films is reported to be 1.0 eV (~1.24 μm)51 or 1.6 eV (~775 nm)52, which is proportional to the free-electron concentration and depends on the temperature and the film/substrate interface state. Hence, the metallic R phase has a lower transmittance and higher reflectance in the IR region (ω < ω p ).…”

Optical properties and structural phase transitions of W-doped VO2(R) under pressure

“…In low-frequency, the reectivity of the R phase is characterized by a continues rise due to the free-electronic contribution. 46,47 The higher reectivity in low-frequency region, indicates higher carrier density in measured samples. Therefore, the pressure dependence of the IR reectivity at low frequencies gives the electronic evolution under pressure, qualitatively.…”