Room temperature Mott metal-insulator transition in V2O3 compounds

Vanadium sesquioxide (V2O3) is an archetypal Mott insulator in which the atomic positions in the unit cell and the electron correlations change as temperature, pressure or doping are varied, paving the way for different structural, electronic and magnetic phase transitions to occur. One example is the purely electronic isostructural Mott transition around room temperature in bulk Cr-doped V2O3 between corundum paramagnetic metallic (PM) and insulating (PI) phases. Remarkably, this phase transition has been elusive in thin film compounds so far. In this work, we demonstrate a room temperature Mott metal-insulator transition (MIT) in 1.5% Cr-doped and pure V2O3 thin films achieved via continuous lattice deformations induced by heteroepitaxy [1]. This MIT is characterized by a colossal change (ΔR/R up to 100,000 %) in room temperature resistivity and a broad range of optical constants values as a consequence of a strain-modulated bandgap. Moreover, the controlled epitaxial strain allows to stabilize the structural, electronic and optical properties of the films at different intermediate states, between the PM and PI phases, inaccessible in bulk materials. Controlling phase transitions in correlated systems by epitaxial strain can offer a radical new approach to create the next generation of Mott devices.

[1] P. Homm et al., APL Materials, 9, 021116 (2021).