Electrons in ferromagnets with domain walls
Electrons in ferromagnets with domain walls
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DOI：
10.1088/0305-4470/36/35/312
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发表时间：
2003-08
期刊：
影响因子：
--
通讯作者：
V. Dugaev;J. Berakdar
中科院分区：
文献类型：
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作者：
V. Dugaev;J. Berakdar
畴壁可以显著改变铁磁金属的电子性质。本文从理论上研究了畴壁对铁磁材料输运性质的影响，并与最近的实验结果进行了比较。在厚畴壁的扩散输运情况下，应用半经典近似，进行局域自旋变换，用相应的没有畴壁但有附加规范场的系统代替有畴壁的系统。由于单粒子电子态在壁面上的重新分布，人们获得了对电阻率的负贡献或正贡献。对于非常窄和/或受约束的畴壁，情况不同。在这种情况下，半经典近似是无效的。取而代之的是基于散射矩阵的方法。然后，畴壁对电阻率产生大的正贡献。因此，相应的磁阻可以非常大，这与最近的实验一致。详细分析了单导电沟道系统中窄畴壁的极限情况，并考虑了电子-电子相互作用的影响。在这种特殊情况下，由于磁畴壁的磁阻可以是非常大的。
Domain walls can significantly modify electronic properties of ferromagnetic metals. In this paper we consider theoretically the influence of domain walls on transport properties of ferromagnetic materials and the results are compared with recent experiments. In the case of diffusive transport through a thick domain wall, the semiclassical approximation is applied and a local spin transformation is performed, which replaces the system with a domain wall by the corresponding system without a domain wall but with an additional gauge field. Due to a redistribution of single-particle electron states at the wall, one obtains then either negative or positive contributions to resistivity. The situation is different for very narrow and/or constrained domain walls. In such a case, the semiclassical approximation is not valid. Instead of this the approach based on scattering matrix is applied. The domain wall then gives rise to a large positive contribution to electrical resistivity. The corresponding magnetoresistance can be therefore very large, which is in agreement with recent experiments. The limiting case of narrow domain walls in systems with a single conduction channel is analysed in detail, with the effects due to electron–electron interaction taken into account. In this particular case the magnetoresistance due to a domain wall can be extremely large.