Realizing Low-Temperature Charge-Transfer-Type Insulating Ground State in Strained V2O3 Thin Film

This is the authors' abstract. We don't add key points for this paper.

Controlling the electronic properties of strongly correlated systems, observing electron–electron correlation-driven metal to insulator transition (MIT) is a key point for the next-generation solid-state Mottronic devices. Thus, the knowledge of the exact nature of the insulating state is an essential need to enhance the functionality of the material. Therefore, we have investigated the electronic nature of the insulating state of a classical Mott insulator V 2 O 3 thin film (epitaxial) using low-temperature (LT) (120 K) resonant photoemission spectroscopy and X-ray absorption near-edge spectroscopy measurements. Temperature-dependent valence band spectra (VBS) reflect the transfer of spectral weight from the metallic coherent band (A M ) near the Fermi level ( E F ) to the insulating Mott–Hubbard screened band (C I ) at a binding energy of around 2.4 eV. Such a transfer of spectral weight upon MIT leads to vanishing of the density of states at E F and opens a band gap. The strong presence of the 3d n L final state is observed near the E F of LT VBS, confirming the presence of an O 2p band participating in low-energy charge fluctuation. This study further endorses the charge-transfer (CT)-type ( U > Δ) insulating nature of a strained V 2 O 3 thin film at LT, unlike its bulk counterpart, which is placed intermediate ( U –Δ) between the CT and the Mott–Hubbard regime. Modifying the electronic ground state of V 2 O 3 to the CT nature via the epitaxial strain in thin films provides a way to tailor the electronic energetics, with its implications to next-generation correlation-derived switching devices.