非晶态Sm-Fe和Sm-Co薄膜的低温磁性

研究了非晶态Sm-Fe和Sm-Co薄膜在1.5—300K的磁性。发现Sm-Fe薄膜中Fe原子磁矩取向存在分散性,Sm-Co薄膜中Co原子有效磁矩随Sm含量的变化与Nd-Co非晶薄膜很相似。决定了Sm-Fe薄膜具有散铁磁结构,Sm-Co薄膜为共线铁磁性结构。Sm原子磁矩≈0。报道了这两个非晶合金系列的矫顽力H_c与成份和温度的依赖关系。发现Sm-Fe薄膜的H_c较高于Sm-Co的值;前者随Sm含量增加而急剧上升,并随温度升高而陡降;后者的H_c在Sm含量≈43at％有极大值,并以指数形式随温度升高而减小。发现低温范围内磁化强度随温度变化与自旋波激发和Stoner激发都有关系。 关键词：

LOW TEMPERATURE MAGNETIC PROPERTIES OF AMORPHOUS Sm-Fe AND Sm-Co THIN FILMS

The low temperature magnetic properties of the amorphous Sm-Fe and Sm-Co thin films are investigated. It is found that there exists a distribution of the orientation of the Fe atomic moment in the Sm-Fe films, and the compositional dependence of the effective magnetic moments of the Co atoms in the Sm-Co films is very similar to that of the amorphous Nd-Co films. The magnetic structures of these two alloy systems are determined: there are asperomagnetic structure for the Sm-Fe thin films and the collinear ferromagnetic structure for the Sm-Co thin films. The magnetic moment of Sm atoms is very close to zero. The strength, temperature and compositional dependences of coercivity for these two amorphous alloy systems are measured. The H_c of Sm-Fe films is much larger than that of Sm-Co films, For the Sm-Fe amorphous films, H_c increases very quickly with increasing of the contants of samarium, and severely drops with increasing of temperature in the very low temperature region. But for the Sm-Co amorphous films, H_c reaches a maximum at about 43 at% Sm, and decreases with increasing of temperature in the exponental form. It is also found that the temperature dependence of magnetization in the low temperature region may be caused by the Bloch spin-wave excitation and Stoner electric excitation simultaneously.