A comparative magnetic study of the DC remanence for the frozen substituted Ba-hexaferrite ferrofluid and some conventional frozen ferrofluids

Recently we have synthesized a new ferrofluid made out of the nanocrystalline substituted barium hexaferrite (BaFe12−2xTixCoxO19 with x=1.2). We compare the variation of the relative DC remanence with temperature for the above ferrofluid with similar curves for four other ferrofluids and among themselves, where all these fluids are frozen in zero field and in 1T external field. An estimate of the effective anisotropy constants for the fine particles in the above five ferrofluids is also obtained, with a value of 250kJ/m3 for the above substituted barium hexaferrite ferrofluid. From the different behavior of the temperature dependence of the relative remanent magnetization of field cooled cobalt ferrofluids with different concentrations we conclude that the remanence is influenced by the formation of particle chains.