Magnetic properties of polycrystalline hexaferrites thin films grown by metal-organic decomposition and pulsed laser deposition: An useful correlation

The evaluation of different routes to prepare polycrystalline thin films based on hexagonal ferrites is of considerable interest due to the excellent properties of these materials as high density magnetic recording media. In particular, the metal-organic decomposition and the pulsed laser ablation deposition have been used for us to grow high coercivity polycrystalline hexaferrite thin films and the results obtained are compared. Using MOD technique BaFe12O19 thin films were deposited onto ZrO2/Si substrates, and the influence of different parameters such as the annealing temperature (500-850 degrees C) and the atmosphere (oxygen and air) during thermal treatments on the magnetic properties are discussed. The formation of barium hexaferrite starts at 600 degrees C, the beneficial role of an oxygen atmosphere in the increasing of coercivity was established and the higher coercivity was 4.0 kOe. Using PLD technique BaFe12O19 and SrFe12O19 thin films were deposited on Si substrates using a Nd-YAG laser apparatus. As-deposited films were annealed in air at temperatures between 600 and 900 degrees C in order to improve the crystallinity. The samples annealed in the temperature range 700-850 degrees C show a higher coercivity (5.75-6.60 kOe) which are among the best values reported in thin films, powders and sintered samples. In all cases the saturation magnetisation of the films is in agreement with values reported in the literature.