Strain-induced structural transition of rutile type ReO2 epitaxial thin films

Rutile-related (tetragonal rutile and monoclinic distorted rutile) ReO2 epitaxial thin films were grown on rutile TiO2 single crystalline substrates by reactive pulsed laser deposition of the Re metal target under a N2O atmosphere. The ReO2 film underwent structural phase transition from the monoclinic to tetragonal phase with the decreasing film thickness, driven by compressive lattice strain from the substrate. X-ray photoelectron spectroscopy and electrical transport measurements revealed that both phases had metallic properties above 25 K. The distinct difference in valence band spectra between the two phases might be due to reconstruction of the band structure dominated by Re 5d t2g.