Er_2AlFe_(16-x)Mn_x化合物的磁性及反常热膨胀  

Magnetic properties and thermal expansion anomaly of Er_2AlFe_(16-x)Mn_x compounds

作　　者：郝延明[1] 赵淼[1] 傅斌[1] 王琳[1] 严达利[1] 

机构地区：[1]天津师范大学物理系,天津300074

出　　处：《物理学报》2006年第9期4906-4911,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50271022)及;天津市自然科学基金(批准号:043602011)资助的课题.~~

摘　　要：通过X射线衍射及磁测量手段研究了Er2AlFe16-xMnx(x=1,2,3,4,6,8)化合物的结构和磁性.研究结果表明Er2AlFe16-xMnx化合物具有六角相的Th2Ni17型结构.采用X射线热膨胀测定法在103—654K的温度范围内测量了Er2AlFe16-xMnx(x=1,2,3,4)化合物的热膨胀性质,发现这些化合物在低温下存在热膨胀反常现象,在居里点附近具有负膨胀性质.对自发磁致伸缩的研究结果表明Er2AlFe16-xMnx化合物中存在着较强的各向异性的自发磁致伸缩,低温下自旋重取向的出现使得化合物的自发体磁致伸缩有所增强.磁测量结果表明Mn的替代导致Er2AlFe16-xMnx化合物的居里温度及自发磁化强度急剧下降,并且使得化合物的磁晶各向异性发生显著改变.The structure and magnetic properties have been investigated by means of X-ray diffraction and magnetization measurements. The Er2AlFe16-xMnx （x = 1, 2, 3, 4, 6 and 8） compounds have a hexagonal ThzNily-type structure. The thermal expansion of Er2AlFe16-xMnx （x = 1, 2, 3, and 4） compounds have been investigated by X-ray dilatometry in the temperature range 103-654K. The results show that there is a thermal expansion anomaly at low temperature and a negative thermal expansion near the Curie temperature. There exists a strong and anisotropic spontaneous magnetostriction in the magnetic state of Er2AlFe16-xMnx compounds. The spin reorientation at low temperature results in an enhancement of the spontaneous volume magnetostrictive deformation of Er2AlFe16-xMnx compounds. Magnetization measurement shows that the Curie temperature and the spontaneous magnetization at 5K of Er2AlFe16-xMnx compounds decrease rapidly with increasing x, and that the Mn substitution for Fe results in obvious change of the magnetic anisotropy.

关 键 词：Er2AlFe16-xMnx化合物 反常热膨胀 自发磁致伸缩 

分 类 号：O482.5[理学—固体物理]