THz magneto-optical studies of 3-D topological Dirac and Weyl semimetals

三维拓扑狄拉克和韦尔半金属的太赫兹磁光研究

• 批准号: 1610554
• 负责人: H. Dennis Drew
• 金额: $ 53.4万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-15 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610554&HistoricalAwards=false
• 关键词: THz; magneto; optical; studies; topological

Non-technical Abstract:The project focuses on the investigations of the optical properties of Weyl and Dirac semimetals. These recently discovered new classes of materials are semimetals with most interesting optical properties. The presence of topological phases results in modifications of the properties in new ways. For example, new states which are protected from scattering are predicted. These features have promise for robust transport of electrical and optical signals useful in future applications. While a number of examples of the Weyl and Dirac semimetals have been identified experimentally, many of the novel predicted optical properties have not yet been investigated. The research experiments in this project fill this gap. The project trains one graduate student, one post-doctoral scholar, and involves one part time undergraduate. Educational outreach activities include development of new lecture demonstration experiments in the optical sciences.Technical Abstract:The experimental investigations of topological 3D Dirac and Weyl materials leverage terahertz optical and magneto-optical techniques. These semimetallic materials are a new class of materials that have relatively low carrier density and conductance, enabling robust tunable optical effects at terahertz frequencies that directly probe the novel properties and low-lying excitations. Magneto-optical experiments in the Voigt geometry offers an extremely sensitive probe of the predicted optical effects from the chiral anomaly that, so far, has only been reported by transport measurements. Kerr and Faraday rotation measurements test predicted magneto-optical-like effects that arise from the underlying Berry curvature (magnetic) monopoles associated with the Weyl nodes. Magneto-optical measurements on the pyrochlore Iridates aim at confirming the presence of the Weyl state below the magnetic transition. Cyclotron resonance investigations of several Dirac semimetals in the extreme quantum limit directly probe the chiral N=0 Landau level. The activities also test recent theories that predict new exotic physical properties of these materials. The electronic band structure of all studied material systems are characterized spectroscopically with FTIR zero-field reflectance and/or cyclotron resonance transmission measurements. The project trains one graduate student, one post-doctoral scholar, and involves one part time undergraduate. Educational outreach activities include development of new lecture demonstration experiments in the optical sciences.

非技术摘要：该项目的重点是外尔和狄拉克半金属的光学性质的调查。这些最近发现的新材料是具有最有趣的光学性质的半金属。拓扑相的存在导致以新的方式修改性质。例如，预测被保护免于散射的新状态。这些特征有希望在未来的应用中有用的电和光信号的鲁棒传输。虽然外尔和狄拉克半金属的一些例子已经被实验确定，但许多新的预测光学性质尚未被研究。该项目的研究实验填补了这一空白。本项目培养研究生1名，博士后1名，非全日制本科生1名。教育推广活动包括在光学science.Technical摘要：拓扑3D狄拉克和Weyl材料的实验研究利用太赫兹光学和磁光技术的新讲座演示实验的发展。这些半金属材料是一类新材料，具有相对较低的载流子密度和电导，能够在太赫兹频率下实现稳健的可调谐光学效应，直接探测新特性和低激发。磁光实验中的Voigt几何形状提供了一个非常敏感的探针的预测光学效应的手征异常，到目前为止，只被报道的运输测量。克尔和法拉第旋转测量测试预测的磁光效应所产生的潜在的贝里曲率（磁）单极与外尔节点。对烧绿石铱酸盐的磁光测量旨在确认在磁性转变以下的外尔态的存在。在极端量子极限下对几种狄拉克半金属的回旋共振研究直接探测了手征N = 0的朗道能级。这些活动还测试了最近预测这些材料新的奇异物理特性的理论。所有研究的材料系统的电子能带结构，其特征在于光谱与FTIR零场反射率和/或回旋共振透射测量。本项目培养研究生1名，博士后1名，非全日制本科生1名。教育推广活动包括开发光学科学的新讲座演示实验。