Spin polarized transport of iron nitride Fe4N: Analysis using a combination of first principles calculation and model calculation
Spin polarized transport of iron nitride Fe4N: Analysis using a combination of first principles calculation and model calculation
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DOI：
10.1002/pssc.200567118
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发表时间：
2006-09
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影响因子：
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通讯作者：
S. Kokado;N. Fujima;K. Harigaya;H. Shimizu;A. Sakuma
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文献类型：
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作者：
S. Kokado;N. Fujima;K. Harigaya;H. Shimizu;A. Sakuma
为了提出一种铁磁体，表现出高度自旋极化的运输，我们分析的自旋极化率的散装Fe 4 N（居里温度：761 K），这是重点考虑到的事实，即铁磁电极包含铁和轻元素增强隧道磁阻效应在室温下。自旋极化比在此由P =（σ - σ）/（σ + σ）定义，其中σ（σ）是上自旋（下自旋）在零温度下的电导率。使用Kubo公式和Slater-Koster紧束缚模型获得电导率，其中参数通过将模型的能带结构拟合到第一原理计算的能带结构来确定。在费米能附近，|P|约为1.0，是bcc-Fe的5.0倍。这表明Fe 4 N作为自旋注入电极是非常有效的。此外，通过比较Fe_4 N与铁磁状态下的fcc-Fe与Fe_4 N的平衡晶格常数，表明N在增加Fe_4 N的铁磁性能方面起重要作用。|P|.（© 2006 WILEY-VCH Verlag GmbH & Co. KGaA，魏因海姆）
To propose a ferromagnet exhibiting a highly spin-polarized transport, we analyze the spin polarization ratio of the bulk Fe4N (Curie temperature: 761 K), which is focused on by taking into account the fact that a ferromagnetic electrode containing Fe and a light element enhances the tunnel magnetoresistance effect at room temperature. The spin polarization ratio is here defined by P = (σ – σ)/(σ + σ), with σ (σ) being the conductivity at zero temperature of up spin (down spin). The conductivity is obtained using the Kubo formula and the Slater-Koster tight binding model, where parameters are determined by fitting the band structure of the model to that of the first principles calculation. In the vicinity of the Fermi energy, |P | takes almost 1.0, which is 5.0 times as large as that of bcc-Fe. It may suggest that Fe4N is very effective as a spin injection electrode. Also, by comparing Fe4N to fcc-Fe in the ferromagnetic state with the equilibrium lattice constant of Fe4N, it is shown that N plays an important role in increasing |P |. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)