Orbital signatures of Fano-Kondo line shapes in STM adatom spectroscopy
Orbital signatures of Fano-Kondo line shapes in STM adatom spectroscopy
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DOI：
10.1103/physrevb.92.235127
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发表时间：
2015-12-15
影响因子：
3.7
通讯作者：
Jacob, David
中科院分区：
文献类型：
--
作者：
Frank, Sebastian;Jacob, David
我们研究了金属基底上磁性吸附原子STM光谱中Fano Kondo线形的轨道起源。为此，我们采用基于密度泛函理论的从头算输运方法，通过局域关联增强，计算了Co原子在（001）和（111）Cu表面的低偏压隧道谱.为了将不同的d轨道与不同的Fano线形状相关联，我们只关联单个的3d轨道，而不是完整的Co 3d壳层。我们发现，近藤峰出现在不同的d水平确实引起不同的Fano功能的电导谱。因此，测量的Fano特征的形状使我们能够得出一些关于负责近藤共振的轨道的结论，尽管实际形状也受到温度，有效相互作用和电荷波动的影响。与简化模型的比较表明，线的形状主要是通过Co原子上的相关d轨道和sp-型轨道的隧道路径之间的干扰的结果。非常重要的是，Fano特征的振幅在轨道之间变化很大，其中3 z（2）轨道由于其与s型传导电子的强直接耦合而具有迄今为止最大的振幅。
We investigate the orbital origin of the Fano-Kondo line shapes measured in STM spectroscopy of magnetic adatoms on metal substrates. To this end we calculate the low-bias tunnel spectra of a Co adatom on the (001) and (111) Cu surfaces with our density functional theory-based ab initio transport scheme augmented by local correlations. In order to associate different d orbitals with different Fano line shapes we only correlate individual 3d orbitals instead of the full Co 3d shell. We find that Kondo peaks arising in different d levels indeed give rise to different Fano features in the conductance spectra. Hence, the shape of measured Fano features allows us to draw some conclusions about the orbital responsible for the Kondo resonance, although the actual shape is also influenced by temperature, effective interaction, and charge fluctuations. Comparison with a simplified model shows that line shapes are mostly the result of interference between tunneling paths through the correlated d orbital and the sp-type orbitals on the Co atom. Very importantly, the amplitudes of the Fano features vary strongly among orbitals, with the 3z(2) orbital featuring by far the largest amplitude due to its strong direct coupling to the s-type conduction electrons.