Charge-Spin Conversions and Nonreciprocal Transport in Chiral Materials

摘要：半导体微电子技术是当今信息技术的核心，也是许多其他应用不可或缺的技术。传统的半导体微电子只利用电子的电荷。已经证明，利用电子的自旋或固有磁性不仅可以大大提高性能，例如显着降低功耗，而且还可以产生根本的新功能，例如非易失性和可重构逻辑。自旋基半导体电子学的一个重要组成部分是电子电荷电流和自旋极化之间的有效相互转换。该项目旨在通过利用手性结构（即具有明显手性的材料）中的电子运动，探索半导体中极化自旋的产生、控制和检测的新方法。产生排列良好的电子自旋的纯电子和无磁方法具有使自旋微电子摆脱任何磁性材料的潜力。因此，该项目将基础科学研究和技术开发结合起来，为学术界和半导体行业提供了一个有效的劳动力发展场所。技术摘要：电荷态和自旋态的有效相互转换是自旋电子学和量子计算的基础研究和器件功能的核心。特别感兴趣的是自旋极化的电产生及其作为电荷信号的读出，而不使用任何铁磁成分。本项目研究了三种不同类型的手性材料：自组装单层手性有机分子、无机手性晶体和有机-无机杂化钙钛矿，结构手性如何产生自旋选择性，以及更一般地说，如何产生线性响应之外的非互易输运效应。该研究的直接目标是阐明手性诱导自旋选择性（CISS）效应的物理基础，其中自旋极化是由具有固有结构手性的材料中的电荷运动产生的。更广泛地说，本研究考察了结构手性在突发性电子激发中的一般作用，以及对称破缺、电子相关和非平凡带拓扑的新输运效应。这项研究可能会为半导体中极化自旋的产生、控制、检测和利用带来一个概念性的新无磁和全电方案。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract:Semiconductor microelectronics is at the heart of today’s information technologies and indispensable for many other utilities. Conventional semiconductor microelectronics utilize only the charge of electrons. It has been demonstrated that harnessing the spin, or the intrinsic magnetic property, of electrons can not only greatly enhance the performance, such as dramatically reduce power consumption, but also produce fundamentally new functionalities such as nonvolatility and reconfigurable logics. An essential ingredient of spin-based semiconductor electronics is the efficient inter-conversions between electronic charge current and spin polarization. This project aims to explore new means of generation, control, and detection of polarized spins in semiconductors by exploiting electron motion in chiral structures, i.e. materials that exhibit distinct handedness. The pure-electronic and magnet-free methods of generating well-aligned electron spins hold the potential of enabling spin-based microelectronics free of any magnetic materials. The project therefore comprises an invaluable combination of basic science research and technology development, providing an effective venue of workforce development for both academia and the semiconductor industry.Technical Abstract:Efficient inter-conversions of charge and spin states are central to fundamental research and device functions of spintronics and quantum computation. Of particular interest are electrical creation of spin polarization and its readout as charge signals without using any ferromagnetic components. This project investigates how structural chirality engenders spin selectivity and, more generally, nonreciprocal transport effects beyond linear response, in three distinct classes of chiral materials: self-assembled monolayers of chiral organic molecules, inorganic chiral crystals, and hybrid organic-inorganic perovskites. An immediate goal of the research is to elucidate the physics underlying the effect of chirality-induced spin selectivity (CISS), where spin polarization emerges from charge motion in materials exhibiting intrinsic structural chirality. More broadly, the research examines the general roles of structural chirality in emergent electronic excitations and novel transport effects from symmetry-breaking, electron correlations, and nontrivial band topology. The research could lead to a conceptually new magnet-free and fully electrical scheme for the generation, control, detection, and utilization of polarized spins in semiconductors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.