Novel transport phenomena in two-dimensional crystals beyond graphene

技术摘要：半导体已经彻底改变了我们的生活。 最近，新型的半导体，如过渡金属二硫属化物和黑磷的单原子层，已经成为可用的。该项目研究了这些材料中的几种新型传输现象。这些输运现象，如无碰撞弹道输运和相干等离子体振荡，在纳米电子器件中起着重要的作用。该项目提供了有关这些输运现象的基本信息，并揭示了固体中非平衡输运所涉及的丰富物理。此外，对几种新的自旋输运现象的研究为这些材料在自旋电子学中的应用提供了信息。该项目通过培训研究生和本科生，让K-12教师参与，扩大代表性不足群体的参与，并加强纳米技术和可再生能源技术的研究基础设施，实现了更广泛的影响。 技术摘要：该项目研究的科学问题是二维晶体中的非平衡弹道电荷和自旋输运，包括过渡金属二硫属化物和磷烯。该项目的方法和途径基于三种超快激光技术：可瞬时注入弹道电荷和自旋电流的量子干涉和控制技术、可分辨电子亚纳米运动的差分泵浦-探测技术以及用于超快和直接检测电子速度的二次谐波产生技术。 本计画的目标是了解和控制二维晶体中的几种新颖输运现象，例如：相干等离子体振荡、弹道电荷输运、弹道纯自旋输运、自旋霍尔效应、自旋极化电荷输运以及自旋古恩效应。

Bon-Technical Abstract:Semiconductors have revolutionized out lives. Recently new types of semiconductors, such as single atomic layers of transition metal dichalcogenides and black phosphorus, have become available. This project studies several types of novel transport phenomena in these materials. These transport phenomena, such as collision-free ballistic transport and coherent plasma oscillation, play important roles in nanoscale electronic devices. This project provides fundamental information about these transport phenomena, and reveals rich physics involved in nonequilibrium transport in solids. Furthermore, the studies of several novel spin transport phenomena provide information for application of these materials in spin-based electronics. This project achieves broader impacts by training graduate and undergraduate students, involving K-12 teachers, broadening participation of underrepresented groups, and enhancing research infrastructure on nanotechnology and renewable energy technology. Technical Abstract:The scientific problem studied in this project is nonequilibrium ballistic charge and spin transport in two-dimensional crystals, including transition metal dichalcogenides and phosphorene. The methods and approaches of this project are based on three ultrafast laser techniques: a quantum interference and control technique that can instantaneously inject ballistic charge and spin currents, a differential pump-probe technique that can resolve sub-nanometer motion of electrons, and a second-harmonic generation technique for ultrafast and direct detection of the velocity of electrons. The goals of this project are to understand and control several novel transport phenomena in two-dimensional crystals, such as coherence plasma oscillation, ballistic charge transport, ballistic pure spin transport, spin Hall effect, spin-polarized charge transport, and spin Gunn effect.