Temperature variation of surface magnetization in antiferromagnetic six lines ferrihydrite nanoparticles.

Six lines ferrihydrite nanoparticles are synthesized following a chemical route. The sample is characterized using x-ray diffractometry, Fourier transform infrared spectroscopy, transmission electron microscopy and vibrating sample magnetometry. Average crystallite size is 5 nm. The sample exhibits superparamagnetic behavior. Magnetization versus magnetic field data in the superparamagnetic region are analyzed considering a distribution in particle size. Temperature dependence of saturation magnetization originating from surface spins and antiferromagnetic susceptibility of particle cores are studied. • Saturation magnetization decreases with increasing temperature. • Magnetization of antiferromagnetic particles is due to uncompensated surface spins. • Surface magnetization of crystals is expected to decrease linearly with temperature. • Temperature variation of saturation magnetization of six lines ferrihydrite is studied. [ABSTRACT FROM AUTHOR]