Charge-Spin Conversions and Nonreciprocal Transport in Chiral Materials

非技术摘要：半导体微电子是当今信息技术的核心，对许多其他公用事业来说也是不可或缺的。传统的半导体微电子只利用电子的电荷。已经证明，利用电子的自旋或本征磁性，不仅可以极大地提高性能，如显著降低功耗，而且还可以产生根本上的新功能，如非易失性和可重构逻辑。基于自旋的半导体电子学的一个重要组成部分是电子荷流和自旋极化之间的有效相互转换。这个项目旨在探索通过利用手性结构中的电子运动来产生、控制和检测半导体中极化自旋的新方法。手性结构是指表现出明显的左手效应的材料。产生排列良好的电子自旋的纯电子和无磁体方法具有使基于自旋的微电子不受任何磁性材料影响的潜力。因此，该项目包括基础科学研究和技术开发的宝贵结合，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：有效的电荷和自旋态的相互转换是自旋电子学和量子计算的基础研究和设备功能的核心。特别令人感兴趣的是电产生自旋极化并将其读出为电荷信号，而不使用任何铁磁组件。这个项目研究了结构手性如何在三类不同的手性材料中产生自旋选择性以及更广泛的非互易输运效应，超越线性响应：手性有机分子的自组装单分子膜，无机手性晶体，以及有机-无机钙钛矿杂化。这项研究的一个直接目标是阐明手性诱导自旋选择性(CISS)效应背后的物理基础，手性诱导自旋选择性是指具有内在结构手性的材料中的电荷运动产生的自旋极化。更广泛地说，这项研究从对称性破缺、电子关联和非平凡的能带拓扑等方面考察了结构手性在紧急电子激发和新的输运效应中的一般作用。这项研究可能会产生一种概念上的无磁铁和完全电气的方案，用于产生、控制、检测和利用半导体中的极化自旋。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.