Magnetic Properties of Magnetite Formed by Biomineralization and Chemical Synthesis

In this work, the magnetic properties of biologically produced magnetite (magnetosomes) by biomineralization process were compared to those of chemically synthesized $Fe_3O_4$. The coercivity of 185 Oe in magnetosomes is connected with the fact that the mean diameter is larger than critical size for transition from superparamagnetic to ferromagnetic behavior. A sharp magnetic transition at 105 K (Verwey transition) is clearly present in magnetosomes while in opposite, this transition is missing in $Fe_3O_4$.