Does the nonmagnetic surface layer exist throughout ferromagnetic nanoparticles?

作者：Lu H M; Zhao C L; Tang S C; Meng X K^*

来源：Journal of Physical Chemistry C, 2007, 111(50): 18585-18588.

DOI：10.1021/jp0757331

The analytic models for size-dependent Curie temperature T,, and saturation magnetization at room temperature M-s of Fe3O4 nanoparticles have been proposed in terms of the size-dependent melting temperature. The T-c(r) and Ms(r) values decrease with a decreasing of the particle radius r. Agreement between model predictions and the corresponding experimental results can be found, which enable us to determine the size dependences of the thickness of nonmagnetic surface layer delta(r) and t(r) in respectively describing T-c(r) and M-s(r) functions. It is found that both delta(r) and t(r) increase with a decreasing of r and t(r) is always twice as large as delta(r). Moreover, the surface layer should be an intrinsic property of ferromagnetic crystals since the nonmagnetic surface layer exists in the whole size range rather than vanishes as r approaches infinite.

• 出版日期2007-12-20
• 单位南京大学