Graphene-based all-proximity-coupled quantum spintronic devices

基于石墨烯的全邻近耦合量子自旋电子器件

• 批准号: 1610447
• 负责人: Jing Shi
• 金额: $ 37.5万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610447&HistoricalAwards=false
• 关键词: Graphene; based; proximity; coupled; quantum

Owing to graphene's unique band structure, two new topological quantum phenomena can emerge: the quantum spin Hall effect (QSHE) and the quantum anomalous Hall effect (QAHE), both offering attractive potential for quantum spintronic applications. A common prerequisite for these two quantum phenomena is strong spin-orbit coupling, either intrinsic or the Rashba type. Of the two phenomena, QAHE requires additional exchange interaction or ferromagnetism in graphene. Although native graphene has neither interaction, its open and flexible structure allows modifications of the properties by proximity coupling to other materials. The proposed quantum phenomena based on quantized anomalous Hall effect can be potentially used for dense, robust, low-power, and scalable non-volatile memory which will drastically improve the performance of the current memory devices based on magnetic tunnel junctions. The non-volatile memory devices are ubiquitous in the modern society. High-performance memory devices based on quantum spintronic phenomena will have a significant impact on low power memory. PI proposes to train the undergraduate and graduate students, especially the underrepresented minority students by engaging them with research projects and teaching them newly developed elective courses. The also PI plans to continue outreach activities to a STEM school by coaching the Science Olympiad events to STEM High school students as well as giving lectures to the summer Physics teachers from southern California high schools during Physics Teacher Summer Academy sponsored by the Physics Department. PI's group has successfully demonstrated the anomalous Hall effect in graphene via the proximity coupling with a magnetic insulator. More recently, PI's group also demonstrated a strong enhancement of spin-orbit coupling via the proximity effect with a transition metal dichalcogenide material (e.g. WS2). In this work, the PI aims to explore the induced effects in all-proximity coupled graphene devices, which acquire new interactions for realizing the predicted quantum effects at relatively high temperatures. Currently few materials are predicted and even fewer materials have been experimentally shown to exhibit QSHE (e.g. HgTe/CdTe quantum wells) and QAHE (e.g. magnetic topological insulators). These materials are extremely difficult to be synthesized or only show the desired properties at extremely low temperatures. The proposed graphene-based devices are ideal systems in which the required interactions can be induced by proximity effects. Those quantum phenomena have not yet been explored in graphene, but it I expected to show many novel and interesting properties, such as quantized transport, robust Hall voltages, pure spin current, etc. These unmatched properties, if demonstrated at high temperatures, can potentially revolutionize the present-day spin electronics. In this proposed research, the PI plans to demonstrate a prototype quantum spintronic memory device based on QAHE. The knowledge learned in the graphene-based devices will deepen our fundamental understanding of two-dimensional electron systems with tunable interactions.

由于石墨烯的独特带结构，可以出现两个新的拓扑量子现象：量子旋转大厅效应（QSHE）和量子异常霍尔效应（qahe），都为量子旋转式应用提供了有吸引力的潜力。 这两种量子现象的常见先决条件是固有的或RashBA类型的强旋轨耦合。在这两种现象中，Qahe需要在石墨烯中的其他交换相互作用或铁磁剂。尽管天然石墨烯既没有相互作用，但其开放且柔性的结构允许通过接近其他材料耦合来修改属性。 基于量化异常霍尔效应的拟议量子现象可以用于致密，健壮，低功率和可扩展的非挥发性内存，这将大大改善基于磁性隧道连接的当前存储器设备的性能。非易失性记忆设备在现代社会中无处不在。基于量子自旋现象的高性能存储设备将对低功率记忆产生重大影响。 PI建议培训本科生和研究生，尤其是代表人数不足的少数族裔学生，通过与他们参与研究项目并教授新开发的选修课程，以培训他们的代表性不足。同样，PI计划通过指导科学奥林匹克运动来继续向STEM学校进行外展活动，以便在物理系赞助的物理学夏季学院期间向来自南加州高中的夏季物理老师讲课。 PI的组通过接近度耦合与磁绝缘子成功证明了石墨烯中的异常霍尔效应。 最近，PI的组还通过邻近效应与过渡金属二甲基元素材料（例如WS2）证明了自旋轨道耦合的强大增强。在这项工作中，PI旨在探索全耐度耦合石墨烯设备的诱导效应，该烯偶联的石墨烯设备获得了新的相互作用，以实现相对较高的温度下预测的量子效应。目前，很少有材料被预测，实验表明的材料甚至更少，展示了QSHE（例如HGTE/CDTE量子井）和Qahe（例如磁性拓扑绝缘子）。 这些材料很难合成，或者仅在极低的温度下显示所需的特性。所提出的基于石墨烯的设备是理想的系统，在该系统中，可以通过接近性效应诱导所需的相互作用。这些量子现象尚未在石墨烯中探索，但我期望显示许多新颖而有趣的特性，例如量化的传输，健壮的霍尔电压，纯自旋电流等。如果在高温下证明，这些无与伦比的特性可以潜在地彻底改变了当今的自旋电子。在这项拟议的研究中，PI计划展示基于Qahe的原型量子旋转记忆装置。 基于石墨烯的设备中学到的知识将加深我们对具有可调相互作用的二维电子系统的基本理解。