Magnetic Investigations of Titanium Doped Gamma Iron Oxides Dispersed in Polymers

Titanium doped gamma iron oxide nanoparticles were prepared by laser pyrolisis. X-Ray studies indicated the presence of $\gamma $ Fe$_{2}$O$_{3}$ and $\beta $ FeO(OH). Small amounts of $\gamma $ titanium maghemite were observed. The average particle size is 5 nm (Transmission Electron Microscopy). Magnetic nanoparticles were dispersed by sonicating a solution of styrene-isoprene-styrene blockcopolymer. The solvent was evaporated by heating at 75 $^{0}$C for 24 hours. The as obtained films were studied by SQUID and ferromagnetic resonance (FMR). The temperature dependence of the magnetization and of hysteresis loops in the temperature range 4 K -- 300 K is reported. The temperature dependence of FMR line parameters in then range 100 K to 450 K is reported. A weak matrix effect within the glass transition range of the polymeric matrix has been observed.