Reduction in anti-ferromagnetic interactions in ion-beam deposited Fe3O4 thin films

Phase pure Fe3O4 thin films of thickness similar to 42nm have been prepared on the Si( 100) substrate by reactive ion beam sputtering in the growth temperature range of 150-250 degrees C. A high degree of phase purity in the 175 degrees C sample has been confirmed by the XRD, Raman shift, and R-T measurements. The polycrystalline films show a sharp Verway transition as supported by temperature dependent resistivity, AC susceptibility, and coercivity behavior. The significant feature of these films is the early saturation of their room temperature magnetization at similar to 400 mT, indicating the presence of low anti-ferromagnetic competitions in sharp contrast to most of the previous reports. The noticeable reduction of anti-phase boundaries and its dependence on growth temperature has been correlated with the energetic ion-beam deposition process, and explained in terms of the of ionic vacancy migration approach of Eerenstein et al. [Phys. Rev. B 68, 014428 (2003)]. The electronic conduction of these films is governed by near-neighbor hopping above 240K and Shklovskii-Efros variable range hopping below this transition temperature. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3699309]