NIST Center for Neutron Research, Gaithersburg, Maryland 20899, USA.
Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Phys Rev Lett. 2014 Oct 3;113(14):147203. doi: 10.1103/PhysRevLett.113.147203. Epub 2014 Oct 2.
The nature of near-surface spin canting within Fe3O4 nanoparticles is highly debated. Here we develop a neutron scattering asymmetry analysis which quantifies the canting angle to between 23° and 42° at 1.2 T. Simultaneously, an energy-balance model is presented which reproduces the experimentally observed evolution of shell thickness and canting angle between 10 and 300 K. The model is based on the concept of Td site reorientation and indicates that surface canting involves competition between magnetocrystalline, dipolar, exchange, and Zeeman energies.
关于 Fe3O4 纳米颗粒中近表面自旋倾斜的本质存在高度争议。在这里，我们开发了一种中子散射不对称分析方法，可定量确定在 1.2 T 时的倾斜角度在 23°至 42°之间。同时，提出了一个能量平衡模型，该模型再现了在 10 至 300 K 之间观察到的壳层厚度和倾斜角的演变。该模型基于 Td 位取向的概念，并表明表面倾斜涉及磁晶各向异性、偶极子、交换和塞曼能之间的竞争。
