Exchange coupling and magnetic anisotropy at Fe/FePt interfaces
Exchange coupling and magnetic anisotropy at Fe/FePt interfaces
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DOI：
10.1103/physrevb.88.174409
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发表时间：
2013-11-13
影响因子：
3.7
通讯作者：
Chantrell, R. W.
中科院分区：
文献类型：
--
作者：
Aas, C. J.;Hasnip, P. J.;Chantrell, R. W.
我们对Fe/FePt/Fe夹层体系中的交换相互作用和磁晶各向异性能（MAE）进行了完全相对论第一性原理计算，以阐明Fe/FePt（软磁/硬磁）界面的存在如何影响Fe/FePt/Fe多层膜的磁性能。在整个研究中，我们比较了几何不放松系统和几何放松系统。我们观察到Fe/FePt界面上的Fe层起着至关重要的作用，因为它与系统软（Fe）相的（各向同性）交换耦合大大降低。此外，该界面铁层对体系的MAE有很大的影响。结果表明，包括Fe/FePt界面的贡献在内，FePt板坯的MAE主要由各向异性位间交换相互作用主导。我们的计算表明，FePt板的MAE相对于相应的体积值的变化是负的，即Fe/FePt界面的存在似乎降低了Fe/FePt/Fe体系的垂直MAE。然而，对于宽松的系统，这种减少是微不足道的。研究还表明，松弛体系的界面交换减少。利用简单的线性链模型，我们证明了交换的减少导致界面处磁化结构的不连续。
We perform fully relativistic first-principles calculations of the exchange interactions and the magnetocrystalline anisotropy energy (MAE) in an Fe/FePt/Fe sandwich system in order to elucidate how the presence of Fe/FePt (soft/hardmagnetic) interfaces impacts on the magnetic properties of Fe/FePt/Fe multilayers. Throughout our study we make comparisons between a geometrically unrelaxed system and a geometrically relaxed system. We observe that the Fe layer at the Fe/FePt interface plays a crucial role inasmuch as its (isotropic) exchange coupling to the soft (Fe) phase of the system is substantially reduced. Moreover, this interfacial Fe layer has a substantial impact on the MAE of the system. We show that the MAE of the FePt slab, including the contribution from the Fe/FePt interface, is dominated by anisotropic intersite exchange interactions. Our calculations indicate that the change in the MAE of the FePt slab with respect to the corresponding bulk value is negative, i.e., the presence of Fe/FePt interfaces appears to reduce the perpendicular MAE of the Fe/FePt/Fe system. However, for the relaxed system, this reduction is marginal. It is also shown that the relaxed system exhibits a reduced interfacial exchange. Using a simple linear chain model, we demonstrate that the reduced exchange leads to a discontinuity in the magnetization structure at the interface.