Role of oxygen content on the magnetic properties of epitaxial anatase and rutile TiO2 thin films

X-Ray diffraction, micro-Raman and static magnetization data at room temperature from epitaxial undoped anatase and rutile TiO(2) thin films are reported. Films are deposited by RF-magnetron sputtering on different substrates and at different deposition parameters. A weak ferromagnetic behaviour at room temperature is observed in each film series, often superimposed to a linear contribution. The different dependence of the magnetization on the oxygen content observed for the different TiO(2) phases is discussed in relation to the tensile strain induced by the different substrates. A complex interplay between oxygen sub-stoichiometry and the interface structural arrangement should be invoked to account for the observed magnetic behaviours.