Size effect of surface magnetic anisotropy in Cu(2)O nanoparticles

作者：Shih Po Hsun; Ji Jhong Yi; Ma Yuan Ron; Wu Sheng Yun^*

来源：Journal of Applied Physics, 2008, 103(7): 07B735.

DOI：10.1063/1.2839331

The thermal deviation of the saturation magnetization of Cu(2)O nanoparticles shows the size effect of a surface magnetic anisotropic energy gap, which is in contrast to the diamagnetism characteristic of bulk Cu(2)O. The thermal deviation of the saturation magnetization exhibits an exponential variation, which is a clear departure from the Bloch T(3/2) law expected for isotropic systems, signaling the onset of magnetic anisotropy, presumably due to the high surface-to-volume ratio of the nanoparticles and the surface atoms which gives rise to polarized moments. We assume a uniaxial anisotropy and adopt the Heisenberg model for the H(a)-aligned moment-carrying Cu(2)O nanoparticles. It is known that the uniaxial anisotropy results in a gap in the energy dispersion. The surface magnetic anisotropic energy gap can be obtained from the fit and decreases with the reducing particle size.

• 出版日期2008-4-1
• 单位东华大学