Afzal Amir Muhammad, Khan Muhammad Farooq, Nazir Ghazanfar, Dastgeer Ghulam, Aftab Sikandar, Akhtar Imtisal, Seo Yongho, Eom Jonghwa
Department of Physics & Astronomy and Graphene Research Institute, Sejong University, Seoul, 05006, Korea.
Department of Nanotechnology & Advanced Materials Engineering, Sejong University, Seoul, 05006, Korea.
Sci Rep. 2018 Feb 21;8(1):3412. doi: 10.1038/s41598-018-21787-y.
Graphene has gigantic potential in the development of advanced spintronic devices. The interfacial interactions of graphene with semiconducting transition metal dichalcogenides improve the electronic properties drastically, making it an intriguing candidate for spintronic applications. Here, we fabricated bilayer graphene encapsulated by WS layers to exploit the interface-induced spin-orbit interaction (SOI). We designed a dual gated device, where the SOI is tuned by gate voltages. The strength of induced SOI in the bilayer graphene is dramatically elevated, which leads to a strong weak antilocalization (WAL) effect at low temperature. The quantitative analysis of WAL demonstrates that the spin relaxation time is 10 times smaller than in bilayer graphene on conventional substrates. To support these results, we also examined Shubnikov-de Haas (SdH) oscillations, which give unambiguous evidence of the zero-field spin-splitting in our bilayer graphene. The spin-orbit coupling constants estimated by two different measurements (i.e., the WAL effect and SdH oscillations) show close values as a function of gate voltage, supporting the self-consistency of this study's experimental results. The gate modulation of the SOI in bilayer graphene encapsulated by WS films establishes a novel way to explore the manipulation of spin-dependent transport through an electric field.
石墨烯在先进自旋电子器件的发展中具有巨大潜力。石墨烯与半导体过渡金属二卤化物的界面相互作用极大地改善了电子性能，使其成为自旋电子应用中一个引人关注的候选材料。在此，我们制备了由WS层封装的双层石墨烯，以利用界面诱导的自旋轨道相互作用（SOI）。我们设计了一种双栅器件，其中SOI通过栅极电压进行调节。双层石墨烯中诱导SOI的强度显著提高，这导致在低温下出现强烈的弱反局域化（WAL）效应。对WAL的定量分析表明，自旋弛豫时间比在传统衬底上的双层石墨烯中短10倍。为了支持这些结果，我们还研究了舒布尼科夫 - 德哈斯（SdH）振荡，这为我们双层石墨烯中的零场自旋分裂提供了明确证据。通过两种不同测量（即WAL效应和SdH振荡）估计的自旋轨道耦合常数作为栅极电压的函数显示出相近的值，支持了本研究实验结果的自洽性。WS膜封装的双层石墨烯中SOI的栅极调制建立了一种探索通过电场操纵自旋相关输运的新方法。
