Temperature-Dependent Electronic Structure of VO₂in the Insulating Phase

Abstract

We have studied the temperature-dependent electronic structure of VO 2 in the insulating phase. The V 3d and O 2p bands become broader and their band edges are shifted toward the Fermi level (E F ) with increasing temperature. The V 2p and O 1s core-level spectra also show a similar temperature dependence. These observations combined with optical spectra indicate that the position of E F relative to the conduction-band minimum is fixed and that the band gap changes mainly below E F . We also point out the possibility that electron-phonon interaction plays an important role in the temperature dependence of spectra in the insulating phase and may drive the metal-insulator transition.

Intrinsic Optical Properties of Vanadium Dioxide near the Insulator−Metal Transition

“…We found that E g decreases by ∼1.5 meV/°C from 55 to 67.3°C, comparable to results of previous infrared and photoemission studies on bulk samples, being about ∼1 meV/°C from ∼0 to 60°C. 23,24 It is also clearly seen that E g remained a finite value at the IMT, which is consistent with the nature of a first-order structural transition. Now we focus on infrared spectra in the close vicinity of IMT.…”

On the Metal–Insulator Transitions in VO2and Ti2O3from a Unified Viewpoint

“…Since these two insulating phases appear by doping small amount of Cr or uniaxial pressure, all the M 1 , M 2 and T phases are classified as Mott-Hubbard and not band insulators. 6) Further experimental studies on this compounds have been carried out [7][8][9][10][11][12][13][14][15][16] and various theories based on the Peierls, 17,18) SpinPeierls 19) and Mott-Hubbard 20,21) mechanisms have been proposed. Band structure calculations with a model GW scheme 22) and discrete-variational-X cluster model calculations including the electron-phonon interaction 23) also have been performed.…”

Role of electron-electron and electron-phonon interaction effects in the optical conductivity ofVO2

“…18,19 However, spectroscopic measurements are difficult for the metallic phase of VO 2 with the bulk crystals because the crystals break into pieces when it cross the MIT. 20 On the other hand, with the thin films, it is difficult to deduce the optical constants precisely from optical measurements because multiple reflections between the film and the substrate should be taken into account.…”