Structual and magnetic properties of MFe2O4 (M=Ni, Mg) nano hollow spheres

作者：Konishi Kensuke^*; Sakurai Taiga; Nagano Yutaro; Manabe Naoto; Morimoto Yugo

来源：Journal of the Korean Physical Society, 2013, 63(3): 672-675.

DOI：10.3938/jkps.63.672

• Hollow spheres
• Ferrite
• Magnetic properties

Sub-micrometer-sized hollow spheres assembled from MFe2O4 (M= Ni, Mg) nanoparticles have been prepared by using the template method with a wet chemical process. A superparamagnetic-type blocking process is observed in the zero-field-cooled (ZFC) and the field-cooled (FC) magnetizations and magnentic susceptibilities. Furthermore, a spin-glass-like behavior due to surface spin freezing is found in Ni-ferrite nanoparticles. The surface spin freezing temperatures T (f) are quite a bit lower than the blocking temperature, and the magnetic field dependence is different between the nanoparticles and the fabricated hollow spheres. The spin-glass nature of the Ni-ferrite nanoparticle is demonstrated by the magnetice field dependence of T (f) following the well known Almeida-Thouless (AT) line. In contrast, the T (f)(H) of the hollow Ni-ferrite sphere hints at failure of the Gabay-Toulouse theory as well as the AT theory.

• 出版日期2013-8