Electron-phonon coupling phenomena in low-dimensional and correlated materials

低维和相关材料中的电子声子耦合现象

• 批准号: RGPIN-2019-07149
• 负责人: Antonius, Gabriel
• 金额: $ 1.75万
• 依托单位: Université du Québec à Trois-Rivières
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748753
• 关键词: Electron; phonon; coupling; phenomena; low

A large number of phenomena arise from the interaction of electrons with the atomic vibrations of a materials-called the phonons. Examples of these phenomena include the electric resistivity, superconductivity, and phonon-assisted optical absorption. The present research program aims to study these phenomena using first-principles calculations, an approach that provides a microscopic description of the materials without any adjustable parameters. Through the various projects, we will implement new methods to study electron-phonon coupling in materials of technological importance. The first subject of research will be the electrical conductivity in energy storage materials. We will study two-dimensional layered materials that can be used for the electrodes of supercapacitors-a type of fast-recharging batteries. For this project, we will implement a new algorithm to compute the phonon-limited electrical conductivity, which relies on a real-space interpolation of the phonon coupling potential. This work will accelerate the optimization of electrode materials for energy storage and offer efficient tools for further research on conducting nanomaterials. Another research direction is superconductivity in cuprates. The role of the electron-phonon interaction for the emergence of superconductivity in these materials is still a scientific debate, since previous calculations were not sufficiently accurate for these systems. We will employ novel algorithms based on many-body perturbation theory to capture the collective behavior of the electrons and compute the electron-phonon interaction strength with unmatched accuracy. The third research direction is the interplay between optical excitations and electron-phonon coupling. Phonon-assisted optical absorption explains the light absorption threshold in many materials, such as silicon. Yet, no method exists to fully describe this phenomenon. The difficulty is that two types of interactions need to be taken into account: the interaction of the electrons with the phonons, and the interaction of the electrons with the holes left after absorbing photons. We will implement a new theory that accounts for both types of interactions. It will allow us to understand the physics of phonon-assisted absorption and compute these phenomena from first principles. After the absorption of a photon in a materials, the optical excitation-called an exciton-can move around and diffuse in another material. We will implement a new method to compute the scattering time of the excitons due to the phonon, which can be directly compared to experiments. It will allow us to study two-dimensional materials of technological importance, such as the transition metal dichalcogenides. This work will help the nanotechnology community understand how the microscopic design of optoelectronic devices affect their optical properties.

大量现象来自电子与声子的原子振动的相互作用。这些现象的例子包括电阻率，超导率和声子辅助光吸收。本研究计划旨在使用第一原理计算研究这些现象，这种方法可对材料进行微观描述，而无需任何可调参数。通过各种项目，我们将实施新的方法来研究具有技术重要性材料的电子偶联。研究的第一个主题将是能源储能材料中的电导率。我们将研究二维分层材料，可用于超级电容器的电极 - 一种类型的快速充电电池。对于这个项目，我们将实施一种新的算法来计算声子受限的电导率，该电导率依赖于声子耦合电位的真实空间插值。这项工作将加速用于储能的电极材料的优化，并为进行纳米材料的进一步研究提供有效的工具。另一个研究方向是丘比特的超导性。电子 - 光子相互作用在这些材料中出现超导性的作用仍然是一场科学争论，因为这些系统对先前的计算不足以准确。我们将采用基于多体扰动理论的新型算法来捕获电子的集体行为，并以无与伦比的精度计算电子相互作用强度。第三个研究方向是光激发与电子音波耦合之间的相互作用。语音辅助光吸收解释了许多材料（例如硅）中的光吸收阈值。然而，没有任何方法可以充分描述这种现象。困难是需要考虑两种类型的相互作用：电子与声子的相互作用，以及电子吸收光子后剩余的孔的相互作用。我们将实施一种新理论，该理论说明两种类型的交互。它将使我们能够理解声子辅助吸收的物理学，并从第一原理中计算这些现象。在材料中吸收光子后，光激励称为激发型罐，并在另一种材料中分散。我们将实施一种新方法来计算由于声子而导致的激子的散射时间，可以将其直接与实验进行比较。它将使我们能够研究具有技术重要性的二维材料，例如过渡金属二甲构元。这项工作将有助于纳米技术社区了解光电设备的微观设计如何影响其光学特性。