Abstract
Transition metal (TM)-doped TiO2 films (TM = Co, Ni, and Fe) were deposited on Si(100) substrates by a sol–gel method. With the same dopant content, Co dopants catalyze the anatase-to-rutile transformation (ART) more obviously than Ni and Fe doping. This is attributed to the different strain energy induced by the different dopants. The optical properties of TM-doped TiO2 films were studied with spectroscopic ellipsometry data. With increasing dopant content, the optical band gap (EOBG) shifts to lower energy. With the same dopant content, the EOBG of Co-doped TiO2 film is the smallest and that of Fe-doped TiO2 film is the largest. The results are related to electric disorder due to the ART. Ferromagnetic behaviors were clearly observed for TM-doped TiO2 films except the undoped TiO2 film which is weakly magnetic. Additionally, it is found that the magnetizations of the TM-doped TiO2 films decrease with increasing dopant content.
Highlights
Magnetic-ion-doped TiO2 with room-temperature ferromagnetism is one kind of promising diluted magnetic semiconductors (DMS)
The survey indicates that titanium, oxygen, iron, cobalt, and nickel are the major components on the surface of these films
For the Fe-doped TiO2 films, the diffraction patterns of the anatase phase are still dominant. These results indicate that the addition of dopant catalyzes the anatase-to-rutile transformation (ART), which are similar to those of the Co-doped [23,33], Ni-doped [34,35], and Fe-doped [36,37,38,39] TiO2 powders
Summary
Magnetic-ion-doped TiO2 with room-temperature ferromagnetism is one kind of promising diluted magnetic semiconductors (DMS). Many efforts have been made to understand the mechanism of ferromagnetism (FM) in magnetic-ion-doped TiO2. The most important point for industrial applications is if such room-temperature FM could originate from the doped matrices and not from the dopant clusters. Some theory models, such as the Ruderman-Kittel-Kasuya-Yosida exchange [4], super exchange [5], double exchange [6], magnetic polarons [7], and F-center exchange mechanism [8], have been used to explain ferromagnetism in transitionmetal-element-doped TiO2. Many controversies still exist in the magnetic origin of DMS. Roomtemperature FM [9] and reversible FM [10] in undoped
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
