Magnetic hysteresis in Fe/SiO2 and Fe/BN granular solids

The magnetic hysteresis behavior of ceramic Fe granular solids is strongly dependent on the type of ceramic matrix and the preparation conditions used. Hysteresis studies in Fe/SiO2 and Fe /BN granular fills showed large differences in the coercivity values, with lower values in the BN matrix. In an attempt to understand the differences in coercivity, derailed structural, microstructural, and magnetic studies have been done in samples prepared by the tandem deposition method and deposition from a composite target both with and without titanium sublimation. Typical granular structure was observed, with grain size in the range of 2-20 nm with the lower size observed in composite fills. The lower coercivities in Fe/BN are due to the formation of amorphous Fe-B particles in BN which have a lower anisotropy. In Fe/SiO2 magnetic properties showed that by varying the deposition method and some of the sputtering parameters (sputtering rate, argon flow, fill thickness, and substrate temperature), it is possible to switch from a relatively magnetically hard sample to a soft sample. (Author)