Epitaxial strain effects on the metal-insulator transition in V2O3 thin films

Effects of epitaxial stress on the metal-insulator transition of V2O3 have been studied for in the form of epitaxial thin films grown on alpha-Al2O3 (0001) and LiTaO3 (0001) substrates. A metallic phase is stabilized down to 2 K in the V2O3 thin film on alpha-Al2O3 (0001), where the a-axis is compressed by 4% owing to large epitaxial stress. On the other hand, the transition temperature T-MI is raised by 20 K from the value of 170 K in bulk samples in the film on LiTaO3 (0001), where the a-axis is expanded. These results suggest an intimate relationship between the a-axis length and T-MI, in V2O3. The conductivity of the metallic ultrathin films shows logarithmic temperature dependence below 20 K, probably due to the Anderson localization in two-dimensional systems. (C) 2003 Elsevier Ltd. All rights reserved.