X-ray Anomalous Scattering of Diluted Magnetic Oxide Semiconductors: Possible Evidence of Lattice Deformation for High Temperature Ferromagnetism

Abstract

We have examined whether the Co ions crystallographically substitute on the Ti sites in rutile and anatase Ti_{1-x}$Co$_{x}$O$_{2-delta}$thinfilmsthatexhibitroom-temperatureferromagnetism.Intensitiesofthex-rayBraggreflectionfromthefilmsweremeasuredaroundthe$K$-absorption-edgeofCo.IftheCoionsrandomlysubstituteontheTisites,theintensityshouldexhibitananomalyduetotheanomalousdispersionoftheatomicscatteringfactorofCo.However,noneoftheanataseandrutilesamplesdidexhibitananomaly,unambiguouslyshowingthattheCoionsinTi$_{1-x}$Co$_{x}$O$_{2-delta}$arenotexactlylocatedattheTisitesofTiO$_2$.TheabsenceoftheanomalyisprobablycausedbyasignificantdeformationofthelocalstructurearoundCoduetotheoxygenvacancy.WehaveappliedthesamemethodtoparamagneticZn$_{1-x}$Co$_{x}$O thin films and obtained direct evidence that the Co ions are indeed substituted on the Zn sites.

arXiv comment5 pages, 4 figures, accepted in PRB

References in corpus (8)

• Co-occurrence of Superparamagnetism and Anomalous Hall Effect in Highly Reduced Cobalt Doped Rutile TiO2 Films
• Magnetic oxide semiconductors
• Electronic Structure and Optical Properties of the Co-doped Anatase TiO${}_2$ Studied from First Principles
• Signature of Carrier-Induced Ferromagnetism in Ti_{1-x}Co_{x}O_{2-delta}: Exchange Interaction Between High-Spin Co 2+ and the Ti 3d Conduction Band
• Hall effect in cobalt-doped TiO${}_{2-\delta }$
• Evolution of ferromagnetic circular dichroism coincident with magnetization and anomalous Hall effect in Co-doped rutile TiO2
• Indication of intrinsic room-temperature ferromagnetism in Ti1-xCoxO2-d thin film: An x-ray magnetic circular dichroism study
• A ferromagnetic oxide semiconductor as spin injection electrode in magnetic tunnel junction

Cited by in corpus (3)

• Role of charge carriers for ferromagnetism in cobalt-doped rutile TiO2
• Ferromagnetism of cobalt-doped anatase TiO${}_2$ studied by bulk- and surface-sensitive soft x-ray magnetic circular dichroism
• Bulk and Surface Magnetization of Co atoms in Rutile Ti_[1-x]Co_xO_[2-delta] Thin Films Revealed by X-Ray Magnetic Circular Dichroism