Epitaxial strain effects on the metal-insulator transition in V_2O_3 thin films

摘要

Effects of epitaxial stress on the metal -insulator transition of V_2O_3 have been studied for in the form of epitaxial thin films grown on α-Al_2O_3 (0001) and LiTaO_3 (0001) substrates. A metallic phase is stabilized down to 2 K in the V_2O_3 thin film on α-Al_2O_3 (0001), where the α-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 LiTaO_3 (0001), where the α-axis is expanded. These results suggest an intimate relationship between the a-axis length and T_(MI) in V_2O_3. The conductivity of the metallic ultrathin films shows logarithmic temperature dependence below 20 K, probably due to the Anderson localization in two-dimensional systems.