Low-Energy Charge Dynamics in Dirac Fermion Materials

技术摘要：这个项目的目标是更好地理解狄拉克点在其能带结构中接近费米能量的材料中的奇异变化动力学。经典的例子是石墨烯；然而，作为体绝缘体的拓扑绝缘体也具有独特的金属手性边缘状态的狄拉克费米子。尽管有许多关于这个主题的理论和实验论文，但关于低频电导率、准粒子相互作用的重要性以及杂质和缺陷在其电子性质中的作用等问题仍然没有得到解决。太赫兹时域光谱学将被用来研究这些材料在这个以前未被探索的频率范围内的响应。除了重要的基本问题外，这些材料还具有从高性能电子设备到拓扑量子计算的新技术功能的潜力。了解太赫兹频率下的电荷动力学是研究其中一些应用的关键组成部分。最后，该项目将在一个迅速崛起的纳米科学领域培养两名研究生和博士后。UCR运营着一个通往研究的夏季桥梁项目，为STEM领域的西班牙裔和/或来自低收入家庭的本科生提供暑期研究支持。每年夏天，这个项目都会有一名学生参与这个项目。非技术摘要：由于其独特的结构，狄拉克·费米子材料，如石墨烯和拓扑绝缘体，具有奇异的电子性质，并显示出广泛的迷人现象，这就是为什么它们吸引了巨大的兴趣。与它们的性质基本相关的是电子对外部电场的响应。本项目的目标是利用时域光谱学研究太赫兹频率下的这种响应。这类在以前未探索的频率范围内的调查与解决与电子如何与缺陷以及彼此相互作用有关的几个问题有关。这些材料具有从高性能电子设备到拓扑量子计算等新技术功能的潜力。除了推进我们的基本理解，这些频率下的电子？S响应的知识对于探索这些新的应用是重要的。最后，该项目将在一个迅速崛起的纳米科学领域培养两名研究生和博士后。UCR运营着一个通往研究的夏季桥梁项目，为STEM领域的西班牙裔和/或来自低收入家庭的本科生提供暑期研究支持。每年夏天，这个项目都会有一名学生参与这个项目。

Technical Abstract:The objective of this project is to better understand the exotic change dynamics in materials with a Dirac point close to the Fermi energy in their band structure. The classic example is graphene; however, topological insulators, which are bulk insulators, also have Dirac fermions in unique metallic chiral edge states. Despite numerous theoretical and experimental papers on this topic, several issues are still unresolved regarding the low-frequency conductivity, the importance of quasiparticle interactions and the role of impurities and defects in their electronic properties. Terahertz time-domain spectroscopy will be used to investigate the response of these materials in this previously unexplored frequency range. Along with important fundamental issues, these materials have the potential for new technological functionality from high-performance electronic devices to topological quantum computing. Understanding the charge dynamics at terahertz frequencies is a crucial component for pursuing some of these applications. Finally, this project will train two graduate students and postdoc in a quickly emerging area of nanoscience. UCR runs a Summer Bridge to Research program that supports summer research for undergraduates in STEM fields who are Hispanic and/or come from low-income families. Each summer, a student in this program will participate on this project.Non-Technical Abstract:As a result of their unique structure, Dirac fermion materials, such as graphene and topological insulators, have exotic electronic properties and display a wide range of fascinating phenomena, which is the reason they have attracted an enormous amount of interest. Fundamentally related to their properties is the response of the electrons to external electric fields. The objective of this project is to investigate this response at terahertz frequencies using time-domain spectroscopy. This type of an investigation in a previously unexplored frequency range is relevant to resolving several issues related to how the electrons interact with defects and with each other. These materials have the potential for new technological functionality from high-performance electronic devices to topological quantum computing. In addition to advancing our fundamental understanding, knowledge of the electron?s response at these frequencies is important for pursuing some of these new applications. Finally, this project will train two graduate students and postdoc in a quickly emerging area of nanoscience. UCR runs a Summer Bridge to Research program that supports summer research for undergraduates in STEM fields who are Hispanic and/or come from low-income families. Each summer, a student in this program will participate on this project.