Thermally induced metal-to-insulator transition in NbO₂ thin films

Modification of the carrier dynamics in correlated oxide systems via epitaxial strain is a promising pathway for the practical realization of energy-efficient electronic devices. Here we present on the thermally induced metal-to-insulator transition (MIT) of epitaxial NbO₂ films grown on Al₂O₃ substrates and the modulation of the MIT temperature via epitaxial strain from the substrate. The metal-insulator transition temperature increased from 910 K to 1066 K with increasing strain. An ultrathin 3.9 nm film consisting of a single strained layer with minimal structural defects yielded a bulk-like sharp transition. The substrate-induced strain offers a new degree of freedom to improve device functionality of MIT materials.