Theory of tunneling magnetoresistance of an epitaxial Fe/MgO/Fe(001) junction
Theory of tunneling magnetoresistance of an epitaxial Fe/MgO/Fe(001) junction
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DOI：
10.1103/physrevb.63.220403
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发表时间：
2001-06-01
影响因子：
3.7
通讯作者：
Umerski, A
中科院分区：
文献类型：
--
作者：
Mathon, J;Umerski, A
报道了外延 Fe/MgO/Fe(001) 结的隧道磁阻 (TMR) 的计算。铁磁和反铁磁配置中结的电导是通过使用适合铁和 MgO 的从头算能带结构的紧束缚带来确定的，无需使用实空间 Kubo 公式进行任何近似。对于大约 20 个原子平面的 MgO 势垒，计算出的乐观 TMR 比率超过 1000%，并且对于所有 MgO 厚度，隧道电流的自旋极化均为正值。研究还发现，即使 MgO 厚度大至接近 20 个原子平面，Fe/MgO/Fe(001) 结中的自旋相关隧道也不完全由伽马点（k（平行于）= 0）处的状态决定。所有这些结果都可以根据 Fe 多数自旋和少数自旋表面光谱密度以及复杂的 MgO 费米表面进行定性解释。
Calculation of the tunneling magnetoresistance (TMR) of an epitaxial Fe/MgO/Fe(001) junction is reported. The conductances of the junction in its ferromagnetic and antiferromagnetic configurations are determined without any approximations from the real-space Kubo formula using tight-binding bands fitted to an ab initio band structure of iron and MgO. The calculated optimistic TMR ratio is in excess of 1000% for an MgO barrier of approximate to 20 atomic planes and the spin polarization of the tunneling current is positive for all MgO thicknesses. It is also found that spin-dependent tunneling in an Fe/MgO/Fe(001) junction is not entirely determined by states at the Gamma point (k(parallel to) = 0) even for MgO thicknesses as large as approximate to 20 atomic planes. All these results are explained qualitatively in terms of the Fe majority- and minority-spin surface spectral densities and the complex MgO Fermi surface.