Control of metal-insulator transition temperature in VO 2 thin films grown on RuO 2 /TiO 2 templates by strain modification

Abstract

Ruthenium dioxide (RuO 2 ) is an ideal buffer layer for vanadium dioxide (VO 2 ) heterostructures due to its high electrical conductivity and matching crystal structure with metallic VO 2 . VO 2 thin films were deposited on single crystal TiO 2 (001) substrates with RuO 2 buffer layers via pulsed laser deposition. The metal-insulator transition temperature (T MIT ) in VO 2 films can be controlled by the epitaxial strain between the VO 2 film and RuO 2 buffer layer by adjusting the buffer layer thickness (10 - 50 nm). We observed a decrease in the T MIT of VO 2 films from 59 °C to 24 °C as the RuO 2 thickness decreased from 50 nm to 10 nm. Additionally, we show that the RuO 2 buffer layer can sustain an intermediate strain state in VO 2 films up to 100 nm in thickness with a subsequently lower T MIT (30 °C). The 10 nm thick RuO 2 buffer layer can reduce the T MIT in VO 2 films by providing a pathway to relieve the strain through grain boundaries.