Comment on “Enhancement of room temperature ferromagnetism in N-doped TiO2−x rutile: Correlation with the local electronic properties” [ Appl. Phys. Lett. 97, 012506 (2010) ]

摘要

Recently an article was published by Drera et al. in thisnjournal investigating the magnetic and electronic propertiesnof ferromagnetic undoped and N-doped TiO2−x rutile.1 Myncomment focuses on the photoemission spectra shown innFigs. 2 and 4 of Ref. 1. In Fig. 2 the authors reported thenTi 2p and N 1s core level spectra of TiO2−x and 4%nN-doped TiO2−x. In Fig. 4 the authors presented the valencenband spectra of TiO2−x and N-doped TiO2−x. They clarifiednthat N doping in rutile TiO2−x would not change the electronicnproperties of TiO2−x, except for the introduction ofnN 2p states above the valence band of TiO2, further thenauthors conclude that the magnetic enhancement of ferromagneticnN-doped TiO2−x was not related to an increase innoxygen vacancies, rather to additional in-gap states. However,nbefore the photoemission spectra of the clean TiOx andnN-doped TiOx samples are obtained, this conclusion is notncompelling.