Magnetic properties of α-Fe_2O_3 nanopallets

摘要

It is the result of a systemic study about uniform hematite nanopallets with length of about 100 nm, width of about 30 nm, and thickness of less than 10 nm. The sample has superparamagnetic(SPM) properties above the blocking temperature of ～16 K. The temperature dependence of magnetization was well fitted by Bloch T^(3/2) law considering the dipolar interaction of the particles. The field dependence of magnetization was fitted with revised Langevin equation.The magnetization of the weak ferromagnetic(WF) canted spins contributes to the linear portion in the high field region;the surface uncompensated spins and the parasitic ferromagnetic moments due to the canted spins both contribute to the particle moments and the superparamagnetic behavior.