Brillouin Light Scattering Studies of Two-Dimensional Layered Materials Systems

二维层状材料是凝聚态物质物理学的千层级糕点。与它们的可食用类似物一样，这些材料由弱结合的层组成，存在于许多不同的品种中，所有这些都具有独特而有趣的属性。然而，对二维层状体系的性质的探索和表征还处于初级阶段，主要是因为它们的新颖性和能够非侵入性地探测经常脆弱的结构的分析技术的数量有限。特别是，对组成这些材料的原子的集体运动--所谓的“声学声子”--的研究很少，而且已经完成的研究是在有限的材料集上进行的。此外，力学性能与其他重要材料性能之间的关系尚未建立。我计划在纪念大学从事的研究项目将利用一种名为布里渊光谱学的光学技术来探测各种大块和超薄的二维层状材料中的声学声子行为，目的是了解这些系统的机械、结构和电子性质之间的相互作用。这些知识对于发展和完善层状材料中与声子相关的现象的理论模型，以及理解极薄系统中电子和声子之间的相互作用至关重要。从技术的角度来看，从拟议研究中获得的信息的广度和数量性质将作为一个机械性能数据库，并作为在这些与工业相关的材料系统中进行声子工程的参考平台。此外，对这些材料的机械性能的了解对于它们在新的柔性电子和光学机械设备以及利用弹性储能的替代能源技术中的预期采用是关键。

Two-dimensional layered materials are the mille-feuille pastries of Condensed Matter Physics.  Like their edible analogs, these materials consist of weakly bound layers and exist in many different varieties, all of which have unique and interesting attributes.  Exploration and characterization of the properties of two-dimensional layered systems, however, is in its infancy, due mainly to their novelty and the limited number of analytical techniques capable of unintrusively probing the often fragile structures. In particular, there have been very few studies of the collective motions of the atoms that make up these materials - so-called 'acoustic phonons' - and those that have been done were carried out on a limited material set. Furthermore, the relationships between the mechanical properties and other important material properties have not been established. The research program that I plan to pursue at Memorial University will utilize an optical technique known as Brillouin spectroscopy to probe acoustic phonon behaviour in a variety of bulk and ultrathin two-dimensional layered materials with the aim of understanding the interplay between the mechanical, structural, and electronic properties of these systems.  This knowledge is critical to the development and refinement of theoretical models of phonon-related phenomena in layered materials, and for understanding the interaction between electrons and phonons in extremely thin systems.  From a technological perspective, the breadth and quantitative nature of the information obtained from the proposed research will serve as a mechanical properties database and as a reference platform for phonon engineering in these industrially-relevant materials systems. Moreover, knowledge of the mechanical properties of these materials is key to their anticipated adoption in new flexible electronic and optomechanical devices, and in alternate energy technologies that utilize elastic energy storage.