Welcome to the Helmholtz-Russia Joint Research Group HRJRG-314:
Defects in magnetic TiO2 (DETI.2)
The electronic, optic and magnetic properties of thin films and nanostructures are in the focus of both basic as well as applied modern research. From the point of view of basic research, understanding the interplay between the above properties allows understanding of basic mechanisms of electronic interaction in solids, especially with respect to new, exotic phenomena. On the other hand, magneto-optics and spintronics are relevant fields in development of new information storage and processing as well as sensor technology.
Within this framework, the major goal of the project is to study the origin of ferromagnetic properties of vanadium or manganese doped anatase TiO2 thin films. For this purpose, structural properties, i.e. presence of point defects in the crystalline lattice or agglomerations of them, oxygen deficiency, magneto-optical effects and electronic/magnetotransport properties will be investigated. The project contains the preparation of oxygen deficient and highly conductive films by sputtering. The films are subsequently doped with vanadium or manganese by means of ion implantation in order to introduce local magnetic moments. Ion implantation has potential in the creation of nanostructures, e.g. by irradiation through lithographically defined masks. In order to guarantee reproducibility of the results, the thin film preparation and doping will be performed in parallel at the HZDR and Moscow State University, the latter using direct magnetic doping during growth.
Characterization will consist of standard techniques such as x-ray diffraction for structural properties, secondary phases and lattice quality as well as magnetometry for determination of the field and temperature dependence of the magnetization. In addition, positron annihilation spectroscopy (PAS) will be used in order to investigate open volume defects on a very local scale. The results will be compared with those from electron paramagnetic resonance (EPR) in order to obtain a deep understanding of the defect evolution in the system. Element-specific investigations of the charge state of the V or Mn impurities as well as their magnetic properties will help to evaluate the origin of the systems overall magnetic properties. Magnetic properties will be analysed via magneto-optical as well as magneto-transport techniques. The focus will be a deeper understanding of the mechanism of magnetic coupling as well as possible applications after finishing the basic research performed in the DETI.2 project.
The project is funded by the Initiative and Networking Fund of the Helmholtz Association.