Atomic-scale imaging of a static and dynamic ordered electronic state pinned by lattice defects

底层原子晶格中的缺陷对一片电子的应变状态、拓扑相缺陷和玻璃状性质有何影响？这些拓扑缺陷和玻璃态的原子尺度性质是什么？在外加电场中，拓扑位相缺陷和无序对动力学性质有什么影响？这些是当电荷密度波-一种有序的电子基态，其特征是周期性的电荷密度和原子位置调制-被底层原子晶格中的缺陷钉扎时观察到的一些不清楚的问题。拟议项目的目标是提供原子尺度的理解，了解静态CDW-没有外加电场-与潜在晶格无序之间的相互作用。这还不包括第一次原子尺度的无序可视化--在外加电场下动态CDW的钉扎。该计划将采用以下方法：(I)使用具有良好定义的CDW态的独立单层；(Ii)通过电子束辐照在这些层中诱导和表征晶格缺陷；(Iii)直接成像和表征静态和动态CDW应变、拓扑缺陷的形成和有序-无序转变作为对晶格缺陷和外加电场钉扎的响应。这将通过同时进行电子辐照、原子尺度成像和光谱分析，以及在透射电子显微镜中对CDW动力学进行原位电偏置来实现。这一项目的结果将有助于理解晶格无序对宏观电子有序态的原子尺度效应、其动力学、相关相变以及量子材料中合理的缺陷设计。

How are the strain state, topological phase defects, and glass–like properties of a sheet of electrons influenced by defects in the underlying atomic lattice? What are the atomic-scale properties of these topological defects and glassy states? What influence do topological phase defects and disorder have on dynamical properties in an applied electric field? These are some of the unclear issues observed when charge density waves – an ordered electronic ground state characterized by a periodic charge density and atomic position modulation – are pinned by defects in the underlying atomic lattice.The goal of the proposed project is to provide an atomic scale understanding of the interaction between a static CDW – without applied electric field – with the underlying lattice disorder. This is in addition to the first atomic-scale visualization of disorder-pinning of a dynamic CDW – under an applied electric field. The proposed project will adopt the following approach: (I) Use free-standing single layers with well defined CDW state (II) Induce and characterize lattice defects in these layers through electron-beam irradiation (III) Directly image and characterize static and dynamic CDW strain, topological defects formation, and order-disorder transitions as response to pinning by lattice defects and applied electric field. This will be done by simultaneous electron-irradiation, atomic-scale imaging and spectroscopy, as well as in-situ electrical biasing for CDW dynamics in the transmission electron microscope (TEM). The results of this project are expected to contribute towards understanding the atomic-scale effect of lattice disorder on a macroscopic electronic ordered state, its dynamics, associated phase transitions, and rational defect design in quantum materials.