Co adatoms on Cu surfaces: Ballistic conductance and Kondo temperature
Co adatoms on Cu surfaces: Ballistic conductance and Kondo temperature
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Cu 表面上的 Co 吸附原子：弹道电导和近藤温度
DOI：
10.1103/physrevb.92.045119
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
E. Tosatti
中科院分区：
文献类型：
--
作者：
P. Baruselli;P. Baruselli;R. Requist;R. Requist;A. Smogunov;M. Fabrizio;E. Tosatti;E. Tosatti
用扫描隧道显微镜探测到的Co吸附原子的Kondo零偏压反常与针尖在表面以上的高度有关，并且这种依赖关系在不同的低指数铜表面上是不同的。在(100)面上，近藤温度随着尖端接近吸附原子而先降低后升高，而在(111)面上几乎不受影响。这些趋势通过结合密度泛函理论和数值重整化群(DFT+NRG)计算得到。吸附原子在两个表面均用S=1安德森模型描述，从头计算有助于确定活性d轨道的对称性。我们在隧道区正确地再现了Co/Cu(100)零偏压反常的Fano线形，但在接触区却没有。在接触区，它可能取决于针尖和接触几何的细节。Co/Cu(111)的线型可能受到表面态的影响，而表面态并不包括在我们的方法中。我们还讨论了对称性的作用，对称性在我们的模型散射几何中是保留的，但在实验条件下很可能是破坏的。
The Kondo zero bias anomaly of Co adatoms probed by scanning tunneling microscopy is known to depend on the height of the tip above the surface, and this dependence is different on different low index Cu surfaces. On the (100) surface, the Kondo temperature first decreases then increases as the tip approaches the adatom, while on the (111) surface it is virtually unaffected. These trends are captured by combined density functional theory and numerical renormalization group (DFT+NRG) calculations. The adatoms are found to be described by an S = 1 Anderson model on both surfaces, and ab initio calculations help identify the symmetry of the active d orbitals. We correctly reproduce the Fano lineshape of the zero bias anomaly for Co/Cu(100) in the tunneling regime but not in the contact regime, where it is probably dependent on the details of the tip and contact geometry. The lineshape for Co/Cu(111) is presumably affected by the presence of surface states, which are not included in our method. We also discuss the role of symmetry, which is preserved in our model scattering geometry but most likely broken in experimental conditions.