ИСТИНА

A continues search for systems that could be considered as Diluted Magnetic Semiconductors (DMS) has been launched by the theoretical prediction of Dietl et al in 2000 [1]. An initial idea was to use these systems for spintronics applications where the spin of curries could be used as well as their charge. Within this framework a lot of compounds have been already studied [see 2-3, and references therein]. A new series of DMS on the basis of titanium dioxide thin films ( 0.3÷0.5mkm ) doped by 3d impurities with one unpaired spin (Co, V and Mn) has been synthesized by magnetron sputtering technique in argon-oxygen atmosphere from ceramic targets. The open hysteresis loops measured by VSM magnetometry have shown the presence of expected ferromagnetic order at room temperature for TiO2:Co and TiO2:V in spite of a tiny level of magnetization in saturation. The magneto-optical (MO) spectra of transversal Kerr effect have proved the ferromagnetic behavior only for our TiO2:Co samples and clarified the presence of Co clusters for the sample that was annealed in vacuum after the sputtering. Transport measurements revealed the n-type of curries either for TiO2:Co or TiO2:V samples. Positron Annihilation Spectroscopy (PAS) was used to check the point and open volume defects by depth-resolved Doppler broadening spectroscopy at the slow-positron-beam SPONSOR [4] with positron energies 27 eV…36 keV. The standard XRD analysis has been used for structural characterization. The values per impurity atom for all samples that reveal magnetization have been calculated and compared with values published in the literature by other groups. The possible difference in exchange mechanisms in TiO2:Co and TiO2:Mn systems is under discussion. This work is supported in part by the Helmholtz-Russia Joint Research Group HRJRG-314 and the Russian Foundation for Basic Research, RFBR #12-02-91321-SIG_a 1. Dietl T, Ohno H, Matsukura F et al., Science 287, 1019 (2000) 2. K.Potzger, NIM B, 272, p.78 (2012) 3. T. C. Kaspar, A. Ney et al., Phys. Rev. B 86, 035322 (2012) 4. W. Anwand, H.-R. Kissener, G. Brauer, Acta Phys. Polonica A 88, 7 (1995)