金屬性扶手型帶狀石墨烯上吸附原子的電遷移力

Abstract

我們研究在金屬性扶手型帶狀石墨烯上吸附原子的電遷移力，特別關注於低能量下 節點特性上的電遷移力，電子於吸附原子周圍散射可引起電遷移力，並且有其他較小 的貢獻，如外加電場。我們的目的為建立由吸附原子引起的等效哈密頓算符，描述 吸附原子在任意位置下，石墨烯軌域的電子，此等效哈密頓算符也考慮碳原子和吸附 原子的混成軌域由sp2至sp3，也包含碳原子上的位能及碳碳間的電子跳躍參數的修正。 金屬性扶手型帶狀石墨烯上的節點特性已經被研究，於節點碳鏈上波函數為 零，我們探討在節點碳鏈及非節電碳鏈中吸附原子的電遷移力，展示藉由調整費米能 階至吸附原子共振態能量得到優化的電遷移力，我們也展示在節點上的吸附原子會留 在節點碳鏈，非節點碳鏈上的吸附原子會被電遷移力驅動至節點碳鏈。我們的成果也 考慮輕微混亂。以及在對稱位置的解析解分析。在本篇論文中吸附原子為氫原子。

We study the electromigration force on an adsorbate in a metallic armchair graphene nanoribbons (AGNRs). Our particular interest is upon the eects of nodal features in the subband (gapless) states and the Fermi energy of the low-biased electron distribution on the electromigration force. The adsorbate electromigration force (AEMF) arises from the scattering of transmitting electrons by the adsorbate and is the so-called wind force. Other minor contributions come from the direct action of the electric eld on the adsorbate when charge transfer between the adsorbate and the AGNR occurs. For our purpose here, we have established an eective adsorbate-induced Hamiltonian for the electrons (- electrons) and for arbitrary adsorbate positions on the AGNR. This eective Hamiltonian has taken care of the local sp2 to sp3 bondings and is shown to be consistent with other work where adsorbate locating only on site of high symmetry were considered. The eective Hamiltonian has included modication to both on-site potentials and nearestneighbor hopping parameters in the vicinity of the adsorbate. The nodal features on the gapless subband of an AGNR, obtained in earlier works, refer to the vanishing of the wave function along certain carbon chains (nodal chain) in the AGNR. We explore the AEMF for adsorbates along a nodal chain and a nonnodal chain. We also demonstrate that it is possible to optimize the AEMF by adjusting the Fermi energy to the resonant energy (where the conductance exhibits either dip or Fano structures). We show that a nodal adsorbate basically stays on the nodal chain and a non-nodal adsorbate could (for one-third on the cases) be driven by the AEMF to move close to the nodal chain. There results remain intact in weak disorder (from edge vacancies). Analytic analysis has been performed at sites of high symmetry. The adsorbate we consider in this work is hydrogen atoms.