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arXiv 1108.3440cond-mat.str-el
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Mn杂质在GaAs(110)面上的磁性

Magnetic properties of Mn impurities on GaAs (110) surfaces

M. Fhokrul Islam C. M. Canali

摘要:

本文基于密度泛函理论计算研究了GaAs样品(110)面上单个和成对的Mn替代杂质。我们重点讨论了这些磁中心的各向异性性质及其对在位关联、自旋轨道相互作用和表面诱导的磁破缺效应的依赖性。对于表面上的Mn杂质,相关联的受主空穴波函数往往是更多的本地化周围的Mn比体GaAs中的杂质。孤立的Mn杂质的磁各向异性能量为1毫电子伏的顺序,并可以涉及到Mn受体空穴的轨道磁矩的各向异性。通常Mn对具有平行排列的自旋磁矩,交换能强烈依赖于表面上的对取向。这些磁性实体的自旋磁矩和交换能不会被自旋-轨道相互作用显著改变,但对现场相关性更敏感。一般的相关性降低了大多数铁磁Mn对的磁各向异性。

英文摘要:

We present a computational study of individual and pairs of substitutional Mn impurities on the (110) surface of GaAs samples based on density functional theory. We focus on the anisotropy properties of these magnetic centers and their dependence on on-site correlations, spin-orbit interaction and surface-induced symmetry-breaking effects. For a Mn impurity on the surface, the associated acceptor-hole wavefunction tends to be more localized around the Mn than for an impurity in bulk GaAs. The magnetic anisotropy energy for isolated Mn impurities is of the order of 1 meV, and can be related to the anisotropy of the orbital magnetic moment of the Mn acceptor hole. Typically Mn pairs have their spin magnetic moments parallel aligned, with an exchange energy that strongly depends on the pair orientation on the surface. The spin magnetic moment and exchange energies for these magnetic entities are not significantly modified by the spin-orbit interaction, but are more sensitive to on-site correlations. Correlations in general reduce the magnetic anisotropy for most of the ferromagnetic Mn pairs.

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