CNR-Istituto di Struttura della Materia, Monterotondo Stazione, (RM), Italy.
Nanotechnology. 2010 Mar 26;21(12):125705. doi: 10.1088/0957-4484/21/12/125705. Epub 2010 Mar 5.
The magnetic properties of ultra-small (3 nm) CoFe(2)O(4) nanoparticles have been investigated by DC magnetization measurements as a function of temperature and magnetic field. The main features of the magnetic behaviour are blocking of non-interacting particle moments (zero-field-cooled magnetization T(max) approximately 40 K), a rapid increase of saturation magnetization (up to values higher than for the bulk material) at low T and an increase in anisotropy below 30 K due to the appearance of exchange bias. The low temperature behaviour is determined by a random freezing of surface spins. Localized spin-canting and cation distribution between the two sublattices of the spinel structure account quantitatively for the observed increase in saturation magnetization.
超小（3nm）CoFe2O4 纳米粒子的磁性通过直流磁化测量作为温度和磁场的函数进行了研究。磁行为的主要特征是阻止非相互作用粒子磁矩（零场冷磁化 T(max)约为 40K），在低温下饱和磁化强度迅速增加（高于体相材料的值），并由于交换偏置的出现导致各向异性增加。低温行为由表面自旋的随机冻结决定。局域自旋倾斜和尖晶石结构的两个亚晶格之间的阳离子分布定量解释了观察到的饱和磁化强度的增加。
