趋近饱和定律在纳米永磁材料磁性研究中的应用

Application of approaching saturation law in the study of magnetic properties of nano-permanent magnetic materials

测量了纳米钴铁氧体样品在温度为5 K和300 K时的磁化曲线和磁滞回线,发现材料在低温5 K时具有很大的矫顽力,随温度升高,矫顽力下降很快.利用趋近饱和定律计算了材料在不同温度时的饱和磁化强度和磁晶各向异性常数.随温度升高,热扰动能增加,饱和磁化强度降低,计算结果与理论分析一致.磁晶各向异性是影响矫顽力的主要因素,计算表明材料在低温5 K时具有很大的磁晶各向异性常数,随温度上升,磁晶各向异性常数快速下降,与矫顽力随温度变化趋势一致.

The magnetization curves and hysteresis loops of nano-cobalt ferrite samples are measured at temperatures of 5 K and 300 K.It is found that the material has large coercivity at low temperature of 5 K,and the coercivity decreases with the increase of temperature.The saturation magnetization and magnetocrystalline anisotropy constant of the material are calculated using the approaching saturation law.As the temperature increases,the thermal disturbance energy increases and the saturation magnetization decreases.The calculated results are consistent with the theoretical analysis.The magnetocrystalline anisotropy is the main factor affecting the coercive force.The calculation results show that the material has large magnetocrystalline anisotropy constant at low temperature of 5 K.With the increase of temperature,the magnetocrystalline anisotropy constant decreases rapidly,which is consistent with the trend of coercive force with temperature.