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arXiv 1006.0591cond-mat.str-el
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金属间化合物Gd(2)Fe(17-x)Ga(x)的从头计算交换作用和磁性

Ab Initio Exchange Interactions and Magnetic Properties of Intermetallic Compound Gd(2)Fe(17-x)Ga(x)

E. E. Kokorina, M. V. Medvedev, I. A. Nekrasov

摘要:

金属间化合物R2 Fe 17作为永磁体具有广阔的应用前景。在技术上,这些系统必须具有比室温高得多的居里温度Tc,并且优选地具有易轴各向异性。目前,化学计量比R2 Fe 17材料中的最高Tc为476 K,这还不够高。有两种可能性,以提高Tc:取代铁离子与非磁性元素或轻元素引入到间隙位置。在本工作中,我们主要研究了Gd(2)Fe(17-x)Ga(x)(x= 0,3,6)化合物中居里温度升高的替代现象。在LSDA方法的框架下,计算了化合物的电子结构和磁性。从头计算交换相互作用参数内的所有最近的Fe离子的Fe亚晶格。利用平均场论中交换参数的理论值,估算了Gd(2)Fe(17-x)Ga(x)的居里温度Tc。获得的Tc值与实验值吻合良好。总磁矩的LSDA计算值与实验值吻合较好。

英文摘要:

Intermetallic compounds R2Fe17 are perspective for applications as permanent magnets. Technologically these systems must have Curie temperature Tc much higher than room temperature and preferably have easy axis anisotropy. At the moment highest Tc among stoichiometric R2Fe17 materials is 476 K, which is not high enough. There are two possibilities to increase Tc: substitution of Fe ions with non-magnetic elements or introduction of light elements into interstitial positions. In this work we have focused our attention on substitution scenario of Curie temperature rising observed experimentally in Gd(2)Fe(17-x)Ga(x) (x=0,3,6) compounds. In the framework of the LSDA approach electronic structure and magnetic properties of the compounds were calculated. Ab initio exchange interaction parameters within the Fe sublattice for all nearest Fe ions were obtained. Employing the theoretical values of exchange parameters Curie temperatures Tc of Gd(2)Fe(17-x)Ga(x) within mean-field theory were estimated. Obtained values of Tc agree well with experiment. Also LSDA computed values of total magnetic moment coincide with experimental ones.

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