Xie Yiqun, Liu Qingwei, Zhang Peng, Zhang Wenqing, Wang Songyou, Zhuang Min, Li Yufen, Gan Fuxi, Zhuang Jun
Department of Optical Science and Engineering, State Key Lab for Advanced Photonic Materials and Devices, Fudan University, Shanghai 200433, People's Republic of China.
Nanotechnology. 2008 Aug 20;19(33):335710. doi: 10.1088/0957-4484/19/33/335710. Epub 2008 Jul 8.
We study the reliability of the lateral manipulation of a single Cu adatom on a Cu(111) surface with single-atom, dimer and trimer apex tips using both semiempirical and first-principles simulations. The dependence of the manipulation reliability on tip height is investigated. For the single-atom apex tip the manipulation reliability increases monotonically with decreasing tip height. For the dimer and trimer apex tips the manipulation reliability is greatly improved compared to that for the single-atom apex tip over a certain tip-height range. Two kinds of mechanism are found responsible for this improvement. One is the so-called enhanced interaction mechanism in which the lateral tip-adatom interaction in the manipulation direction is improved. The other is the suspended atom mechanism in which the relative lateral trapping ability of the tip is improved due to the strong vertical attraction of the tip on the adatom. Both mechanisms occur in the manipulations with the trimer apex tip, while in those with the dimer apex tip only the former is effective. Moreover, we present a method to realize reversible vertical manipulation of a single atom on a Cu(111) surface with the trimer apex tip, based on its strong vertical and lateral attraction on the adatom.
我们使用半经验和第一性原理模拟方法，研究了在Cu(111)表面上，使用单原子、二聚体和三聚体顶点尖端对单个Cu吸附原子进行横向操纵的可靠性。研究了操纵可靠性对尖端高度的依赖性。对于单原子顶点尖端，操纵可靠性随着尖端高度的降低而单调增加。对于二聚体和三聚体顶点尖端，在一定的尖端高度范围内，与单原子顶点尖端相比，操纵可靠性有了很大提高。发现有两种机制导致了这种提高。一种是所谓的增强相互作用机制，其中在操纵方向上的横向尖端-吸附原子相互作用得到改善。另一种是悬浮原子机制，其中由于尖端对吸附原子的强烈垂直吸引力，尖端的相对横向捕获能力得到提高。这两种机制都发生在使用三聚体顶点尖端的操纵中，而在使用二聚体顶点尖端的操纵中，只有前者有效。此外，基于三聚体顶点尖端对吸附原子的强烈垂直和横向吸引力，我们提出了一种在Cu(111)表面上对单个原子进行可逆垂直操纵的方法。
