Surface and exchange anisotropy fields in MnFe2O4 nanoparticles:: Size and temperature effects
Surface and exchange anisotropy fields in MnFe2O4 nanoparticles:: Size and temperature effects
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DOI：
10.1063/1.369383
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发表时间：
1999-05-15
影响因子：
3.2
通讯作者：
Pelegrini, F
中科院分区：
文献类型：
--
作者：
Bakuzis, AF;Morais, PC;Pelegrini, F
利用磁共振角度测量方法研究了球形MnFe2O4磁性纳米颗粒的表面各向异性场和交换各向异性场随温度和粒径的变化规律。共振场是角相关场和角无关场的组合，两者都受表面各向异性场的影响，而表面各向异性场又遵循d - α幂律，α非常接近于单位。角相关分量探测表面各向异性场，角无关分量探测交换各向异性场。在100 ~ 250 K的温度范围内，MnFe2O4纳米颗粒表面存在负的各向异性场，且随粒径的减小而增大，表明MnFe2O4纳米颗粒表面的自旋呈径向方向。(C) 1999年美国物理研究所。[s0021 - 8979(99) 04510 - 7]。
Angular measurements of magnetic resonance are used to investigate the surface anisotropy field as well as the exchange anisotropy field in spherical MnFe2O4 magnetic nanoparticles as a function of temperature and particle diameter (D). The resonance field is a combination of angular dependent and angular independent fields, both affected by the surface anisotropy field, which in turn follows a D-alpha power law, with alpha very close to unity. The angular dependent component probes the surface anisotropy field while the angular independent component probes the exchange anisotropy field. In the temperature range from 100 to 250 K a negative surface anisotropy field is found, which increases as the particle size is reduced, indicating a radial orientation of the spins at the MnFe2O4 nanoparticle surface. (C) 1999 American Institute of Physics. [S0021-8979(99)04510-7].