title: Charge and magnetic states of rutile TiO2 doped with Cr ions.
abstract: We observe that the electronic and magnetic properties of Cr-doped rutile TiO2 single crystals are highly dependent on growth conditions. The ferromagnetic component of magnetic susceptibility is observed to be enhanced for samples grown under oxygen-rich conditions. To understand the charge state of Cr dopants and their role in response to an external magnetic field, we carry out density functional theory calculations for Cr-doped rutile TiO2. Using the results of formation energy calculations in the presence of oxygen vacancies and Cr atom substitution at the Ti sites, we demonstrate that the Cr3+ state is a source of Curie-Weiss-type magnetic response, whereas the Cr4+ defect states contribute to the ferromagnetic component. We also provide the electronic structures of various defect configurations and attempt to explain the optical and electronic properties of the Cr-doped system.
authors.affiliation: CSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Rokyeon
authors.initials: R
authors.lastname: Kim
authors.forename: Suyeon
authors.initials: S
authors.lastname: Cho
authors.forename: Won-Goo
authors.initials: WG
authors.lastname: Park
authors.forename: Deok-Yong
authors.initials: DY
authors.lastname: Cho
authors.forename: Se-Jung
authors.initials: SJ
authors.lastname: Oh
authors.forename: Romuald
authors.initials: R
authors.lastname: Saint-Martin
authors.forename: Patrick
authors.initials: P
authors.lastname: Berthet
authors.forename: Je-Geun
authors.initials: JG
authors.lastname: Park
authors.forename: Jaejun
authors.initials: J
authors.lastname: Yu
mesh_terms: D002857:Chromium / Q000737:chemistry*; D004583:Electrons; D060328:Magnetic Phenomena; D008956:Models, Chemical; D011789:Quantum Theory; D014025:Titanium / Q000737:chemistry*
chemical_list: D002857:Chromium; C009495:titanium dioxide; D014025:Titanium