CNIC: U.S.-Swedish Engineering Research on Spin Blockaded Transport and Onset of Wigner Crystallization in All Electric Spin Valves

CNIC：美国-瑞典关于所有电动自旋阀中自旋封锁输运和维格纳结晶开始的工程研究

• 批准号: 1341789
• 负责人: Marc Cahay
• 金额: $ 5.33万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1341789&HistoricalAwards=false
• 关键词: CNIC; U.S.; Swedish; Engineering; Research

To realize the full potential of spin-based devices, ways must be found to inject, manipulate, and detect the spin of the electron by purely electrical means. Recently, the Principal Investigator (PI) successfully demonstrated that lateral spin orbit coupling (LSOC) can be used to create a strongly spin-polarized current by purely electrical means; that is, in the absence of any applied magnetic field. The PI proposes to extend these studies to spin valve structures composed of a quantum dot or wire coupled to the source and drain via asymmetrically biased quantum point contacts (QPCs). With an asymmetric bias on the gates of the two QPCs, their spin filtering, when combined with Coulomb blockaded transport through the active channel, should lead to spin-blockaded transport through the spin valve. When operated close to threshold, all electrical spin valves could also be used to investigate new many-body effects, such as electrically controlled spontaneous spin polarization, Wigner crystallization and formation of spin lattices in nanoscale devices, which are burgeoning fields of spintronics research.Intellectual Merit:The proposed planning visit to initiate research with Swedish partners at the University of Linkoping to provide the first theoretical investigation of the Coulomb/Spin Blockades and Wigner Crystallization regimes of operation in all-electric spin valves in the presence of LSOC. Since these many-body effects cannot be modeled using a one-particle Hamiltonian approach, the cooperative technical approach will be to develop a theoretical framework based on a multi-particle Fock space and steady-state rate equations, and to calculate the conductance of these spin valves. Theoretical efforts will complement recent experimental efforts at the University of Cincinnati to create all electric spin valves and other recent reports on quantum manipulation of single spins in quantum dots which rely on subtle spin correlation effects leading to intriguing non-linear transport phenomena such as Negative Differential Region (NDR), multiple NDR, and bistability.Broader Impacts:A thorough understanding of the Coulomb and Spin Blockades, and Wigner crystallization in all electric spin valves in the presence of LSOC would be a major milestone in the field of spintronics. A deep understanding of these non-linear effects in strongly correlated systems will contribute to future advancement in fields where non-equilibrium dynamics are involved. If successful, this project is likely to theoretically produce the first simulator that includes the effects of Coulomb and Spin blockade and models spin transport in nanoscale devices in the presence of LSOC. The software developed will be useful to investigate heterostructure parameters for design and fabrication of all electric spin valves for applications in spin-based sensors, spin filters, multilevel logic circuits and data storage applications. The project described is intended to catalyze new collaboration between the School of Electronics and Computing Systems at the University of Cincinnati and the Department of Physics, Chemistry and Biology in Linkoping, Sweden. This effort will serve as a precursor for long-term collaboration between Cincinnati and Linkoping Universities to engage undergraduate and graduate physics/engineering students in both countries through a research exchange program during which the students would benefit from the guidance of engineers and physicists with complementary expertise.

为了充分发挥基于自旋的器件的潜力，必须找到通过纯电手段注入、操纵和检测电子自旋的方法。 最近，首席研究员（PI）成功证明了横向自旋轨道耦合（LSOC）可以通过纯电的方式产生强自旋极化电流；也就是说，在没有任何外加磁场的情况下。 PI 建议将这些研究扩展到由量子点或量子线组成的自旋阀结构，该结构通过不对称偏置的量子点接触（QPC）耦合到源极和漏极。 由于两个 QPC 的栅极上存在不对称偏压，它们的自旋过滤与通过主动通道的库仑阻断传输相结合，应该会导致通过自旋阀的自旋阻断传输。 当接近阈值操作时，所有电动自旋阀也可用于研究新的多体效应，例如电控自发自旋极化、维格纳结晶和纳米级器件中自旋晶格的形成，这些都是自旋电子学研究的新兴领域。 智力优点：拟议计划访问林雪平大学与瑞典合作伙伴一起启动研究，以提供关于自旋电子学研究的首次理论研究 在 LSOC 存在的情况下，全电动自旋阀的库仑/自旋封锁和维格纳结晶操作方式。 由于这些多体效应无法使用单粒子哈密顿方法进行建模，因此合作技术方法将是开发基于多粒子福克空间和稳态速率方程的理论框架，并计算这些自旋阀的电导。 理论工作将补充辛辛那提大学最近的实验工作，以创建所有电动自旋阀和其他关于量子点中单自旋的量子操纵的最新报告，这些报告依赖于微妙的自旋相关效应，导致有趣的非线性输运现象，例如负微分区域（NDR）、多重NDR和双稳态。更广泛的影响：对库仑和自旋封锁以及维格纳结晶的全面理解 LSOC 电动自旋阀的出现将成为自旋电子学领域的一个重要里程碑。 对强相关系统中这些非线性效应的深入理解将有助于非平衡动力学领域的未来进步。 如果成功，该项目理论上可能会产生第一个模拟器，其中包括库仑和自旋封锁的影响，并在 LSOC 存在的情况下模拟纳米级器件中的自旋输运。 开发的软件将有助于研究异质结构参数，用于设计和制造所有电动自旋阀，这些电动自旋阀适用于基于自旋的传感器、自旋过滤器、多级逻辑电路和数据存储应用。所述项目旨在促进辛辛那提大学电子与计算系统学院与瑞典林雪平物理、化学和生物系之间的新合作。 这项努力将成为辛辛那提大学和林雪平大学之间长期合作的先驱，通过研究交流计划吸引两国物理/工程专业的本科生和研究生，在此期间，学生将受益于具有互补专业知识的工程师和物理学家的指导。