Origins of distinctly different behaviors of Pd and Pt contacts on graphene.
Origins of distinctly different behaviors of Pd and Pt contacts on graphene.
复制标题
DOI：
10.1103/physrevlett.103.066802
复制
发表时间：
2009-08
影响因子：
8.6
通讯作者：
Qiming Wang;J. Che
中科院分区：
文献类型：
--
作者：
Qiming Wang;J. Che
基于第一性原理计算，我们提出了一种交换-转移机制来理解Pd和Pt在石墨烯上不同的接触行为。该机制的特点是石墨烯上转移到Pd d{xz}+d{yz}轨道上的pi电子主要被Pd d{z；{2}}轨道上的电子补偿。这种机制导致了Pd和石墨烯之间更多的相互作用状态和传输通道。最重要的是，该机制在石墨烯上保留了足够的pi电子。我们发现，当Pd覆盖在石墨烯上时，Pd层中与石墨烯晶格匹配所必需的拉伸应变在促进这种交换转移中起着关键作用，而在铂层中类似的应变不会导致这种机制。
Based on first-principles calculations, we propose an exchange-transfer mechanism to understand the distinctively different behaviors of Pd and Pt contacts on graphene. The feature of the mechanism is that the pi electrons on the graphene transferring to the Pd d_{xz} + d_{yz} orbital are largely compensated by the electrons from the Pd d_{z;{2}} orbital. This mechanism causes more interaction states and transmission channels between the Pd and graphene. Most importantly, the mechanism keeps enough pi electrons on the graphene. We show that a tensile strain in the Pd layer, necessary to match the graphene lattice, plays a key role in stimulating this exchange transfer when Pd covers on graphene, while a similar strain in the Pt layer does not cause such a mechanism.