Probing local electronic structure in 2D heterostructures

探测二维异质结构中的局域电子结构

• 批准号: 2108771
• 金额: --
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2108771
• 关键词: Probing; local; electronic; structure; 2D

Starting with the semi-metallic graphene, the library of two-dimensional materials (2DMs) has expanded rapidly to include metals, semiconductors, insulators and more. Strongly correlated 2D materials are emerging as a fascinating area of research, with reports of 2D superconductors, magnets and even 2D topological insulators (2D TIs). Associated with this, phase transitions in 2D are fundamentally different from in three dimensions, leading to new Physics to explore. With the award of the Nobel Prize in Physics 2017 for the study of topological phase transitions and topological phases of matter, and the continued rise of 2DMs, this highlights exciting new avenues of research. The ability to simply stack different 2DMs to create complex heterostructures with new functional properties adds not only important degrees of freedom in designing devices, but also great hope for achieving real technological advances.Probing the local electronic structure and properties of 2D materials is thus an outstanding challenge and opportunity. The 2D stacks are typically only a few micrometres across, necessitating local probes. We have shown that angle resolved photoemission spectroscopy with submicrometre spatial resolution (nanoARPES) is capable of directly measuring the layer dependent electronic structure in these stacks. This opens new avenues of research, allowing us to directly interrogate interaction phenomena such as moire effects and renormalisation. To complement the nanoARPES experiments, scanning probe microscopy (SPM) can resolve topographic, electronic, ferroic and magnetic structure with nanometre precision and under a range of environmental conditions. For 2DM, this enables studying how local electronic and ferroic properties change with the number of layers, distinguishing edge and 'bulk' effects, and probing spatial inhomogeneities. For example, with a 2D TI, SPM will be able to probe the bulk insulating and edge conducting states and examine spatial correlations at the phase transition.This project is thus an exciting opportunity to study new Physics in new materials using new technology. The primary focus will be to apply high-resolution photoemission and SPM techniques to study electronic and functional properties of 2D materials at the nanoscale. This will capitalise on the unique SPM facility at Warwick for low temperature (base temperature < 2 K) atomic force microscopy with vectoral magnetic field (9x1x1 T) and optical access for time-resolved photodependent measurements, complemented by a new state-of-the-art ambient AFM. Although some of the 2D heterostructure samples will be fabricated in house, others will be sourced from our international collaborators.

从半金属石墨烯开始，二维材料 (2DM) 库迅速扩展至包括金属、半导体、绝缘体等。强相关二维材料正在成为一个令人着迷的研究领域，有关于二维超导体、磁体甚至二维拓扑绝缘体（2D TI）的报道。与此相关的是，二维中的相变与三维中的相变根本不同，从而导致新的物理学需要探索。随着 2017 年诺贝尔物理学奖因对物质的拓扑相变和拓扑相的研究而获得，以及 2DM 的持续兴起，这凸显了令人兴奋的新研究途径。简单地堆叠不同的 2DM 来创建具有新功能特性的复杂异质结构的能力，不仅为设计器件增加了重要的自由度，而且为实现真正的技术进步带来了巨大的希望。因此，探测 2D 材料的局域电子结构和特性是一个突出的研究领域。挑战与机遇。二维堆栈的宽度通常只有几微米，因此需要局部探针。我们已经证明，具有亚微米空间分辨率的角分辨光电子能谱（nanoARPES）能够直接测量这些堆栈中层相关的电子结构。这开辟了新的研究途径，使我们能够直接询问莫尔效应和重正化等相互作用现象。为了补充 nanoARPES 实验，扫描探针显微镜 (SPM) 可以在一系列环境条件下以纳米精度解析形貌、电子、铁性和磁性结构。对于 2DM，这使得研究局部电子和铁性如何随层数变化、区分边缘和“体”效应以及探测空间不均匀性成为可能。例如，通过 2D TI，SPM 将能够探测体绝缘和边缘导电状态，并检查相变时的空间相关性。因此，该项目是使用新技术研究新材料中新物理的令人兴奋的机会。主要重点是应用高分辨率光电发射和 SPM 技术来研究纳米级二维材料的电子和功能特性。这将利用沃里克独特的 SPM 设施，用于低温（基础温度 < 2 K）原子力显微镜，具有矢量磁场 (9x1x1 T) 和用于时间分辨光相关测量的光学通道，并辅以新的先进技术- 艺术环境 AFM。尽管一些二维异质结构样品将在内部制造，但其他样品将来自我们的国际合作者。