石墨烯電子具有被稱為能谷類自旋的新自由度，可用於實現能谷電子學—一種利用能谷作為信息載子的電子學。吳教授的團隊提出了一種全電性控制的能谷閘，而其操作原理源自於所謂的“能谷-軌道交互作用（VOI）”電流過濾現象。其將能谷類自旋與平行平面之外加橫向電場耦合，形式恰類似自旋軌道交互作用（SOI）。在本研究中，我們使用最鄰近緊束縛模型模擬單層/雙層扶手椅石墨烯奈米帶（ML/BL AGNR）能谷閘中電子的彈道運輸。能谷閘的基本單元由一對能谷濾波器組成。二濾波器之平面橫向電場方向呈平行或反平行排列。一濾波器“極化”（入射）電子到特定一個能谷，然後根據平行或反平行排列，而讓第二個濾波器放行或阻擋來自第一個濾波器的電子。雜質和缺陷散射是介觀運輸研究中的重要課題。由於大的動量改變才足以“翻轉”能谷類自旋，我們的構架於VOI原理上的能谷閘自然是穩定邏輯閘的最佳之選。此篇論文另探索了各種有關子課題，如界面散射，長距和短距雜質以及粗糙邊緣散射，濾波間間距，雙能谷閘以及單軸應變等方面的影響。

Graphene electrons carry the novel degree of freedom known as valley pseudospin that can be used to implement valleytronics ― electronics with valley pseudospin being the information carrier. Wu’s group has proposed an all electrically driven valley valve that filters current based on the so-called “valley-orbit interaction (VOI)”, which couples valley pseudospin to in-plane, transverse electric field and is an analogue of spin-orbit interaction (SOI). In this study we simulate the ballistic transport of electrons in valves of monolayer/bilayer armchair graphene nanoribbon (ML/BL AGNR), using nearest-neighbor tight-binding model calculation. The basic unit of a valve consists of a pair of valley filters with in-plane, transverse DC electric fields aligned in parallel or anti-parallel. A filter specializes in “polarizing” (the incident) electrons to one of the valleys; a second filter then allows passage of or blocks electrons from the first depending on the parallelism or anti-parallelism, respectively. Impurity and defect scatterings are important issues in mesoscopic transport studies. Owing to the great momentum change it requires to “flip” the valley pseudospin, our VOI-based valley valve is a natural candidate for robust logic gate. Various effects, such as those of interface scattering, long- and short-range impurity and edge roughness scatterings, inter-filter spacing, increasing number of valley filters, and uniaxial strain were explored to verify such point.

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