Magnetic anisotropy in Ni2MnGa -: art. no. 134422
Magnetic anisotropy in Ni2MnGa -: art. no. 134422
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DOI：
10.1103/physrevb.65.134422
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发表时间：
2002-04-01
影响因子：
3.7
通讯作者：
Nieminen, RM
中科院分区：
文献类型：
--
作者：
Enkovaara, J;Ayuela, A;Nieminen, RM
我们在这里研究，在密度泛函理论，磁各向异性能（MAE）在Ni2MnGa，这是一个原型的磁性形状记忆合金。我们计算的MAE，这是一个关键属性的磁性形状记忆效应，为四相结构与不同比例的c和a的晶格常数，再现实验易轴的结构的压缩和伸长。当实验样品的非化学计量比用一个简单的刚性带近似建模时，在MAE的实际值的理论和实验之间也发现了良好的协议。此外，我们还估算了磁致伸缩系数，证实了普通磁致伸缩与磁形状记忆效应之间的差异。同样重要的是，我们研究的微观起源的MAE在Ni2MnGa的自旋密度和轨道矩各向异性和扩展的分析的轨道矩各向异性的三元化合物。这些结果表明，最大的贡献MAE来自Ni，尽管在Mn网站的较大的磁矩。
We study here, within the density-functional theory, the magnetic anisotropy energy (MAE) in Ni2MnGa which is a prototype of a magnetic shape-memory alloy. We calculate the MAE, which is a key property for the magnetic shape-memory effect, for tetragonal structure with different ratios of the c and a lattice constants, reproducing the experimental easy axes both in compression and elongation of the structure. Good agreement between the theory and the experiments in the actual values of the MAE is also found when the nonstoichiometry of the experimental samples is modeled with a simple rigid band approximation. In addition, we estimate the magnetostriction coefficient, confirming the difference between the ordinary magnetostriction and the magnetic shape-memory effect. Equally important, we study the microscopic origin of the MAE in Ni2MnGa with the spin density and the orbital moment anisotropy and extend the analysis of the orbital moment anisotropy to the ternary compounds. These results show that the largest contribution to the MAE comes from Ni, in spite of the larger magnetic moment in the Mn sites.