CAREER: A platform for broadband terahertz spectroscopy of 2D materials and heterostructures

摘要用于研究纳米材料性质的方法从根本上受到所谓衍射极限的限制。这个极限将被研究材料的大小限制在用于探测它的辐射波长的大致范围内。该项目使用波长为数百微米的太赫兹辐射来探测新兴的二维材料，这些材料具有独特和前所未有的特性，包括超导性和磁性。通过将太赫兹辐射限制在所研究的小型材料表面，该技术绕过了衍射极限，并为这些迷人材料的动态响应和电子特性提供了新的理解。该研究还促进了对下一代高频通信技术应用的小型芯片上高频辐射传输的理解。该项目在很大程度上依赖于本科生和研究生的参与，并为这些学生提供了一个学习前沿实验技术的渠道。该项目的几项活动侧重于招募和留住代表性不足的学生从事科学领域的长期职业。该项目由材料研究部（DMR）和促进竞争研究的既定计划（EPSCoR）共同资助。技术摘要太赫兹（THz）时域光谱学使人们对物质的性质有了更深入的了解，并已成为研究材料低能物理和动力学的宝贵工具。太赫兹光谱存在于能量和时间尺度的范围内，这在具有强相互作用的材料中尤为重要。将该技术应用于新兴的相关二维范德华异质结构，以表征目前尚未很好理解的基态和相互作用，将是非常有利的。本项目设计并优化了一个用于微观材料太赫兹光谱的平台，首先关注二维超导体和磁体。该技术利用平面波导和光泵浦光导开关，利用片上单周期太赫兹脉冲对这些材料进行太赫兹时域光谱分析，从而获得低能量激发和动态的光谱信息。该平台为非常规二维超导体中可能的配对机制和二维磁体的弛豫动力学提供了急需的见解。它也可以很容易地应用于微观材料，并在优化亚衍射太赫兹光谱和高频通信的路线上有广泛的应用。该项目由材料研究部（DMR）和促进竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical AbstractMethods used in investigating properties of nanoscale materials is fundamentally restricted by what is called the diffraction limit. This limit constrains the size of a material under investigation to roughly the wavelength of the radiation used to probe it. This project uses terahertz radiation with wavelengths of hundreds of micrometers to probe the emerging two-dimensional materials that have unique and unprecedented properties including superconductivity and magnetism. By confining the terahertz radiation to the surface of the small-scale materials being studied, this technique circumvents the diffraction limit and offers new understanding about the dynamic response and electronic properties of these fascinating materials. The research also advances understanding of high frequency radiation transmission on small-scale chips for applications in next generation high frequency communications technology. The project heavily relies on undergraduate and graduate student involvement and provides an outlet for these students to learn cutting-edge experimental techniques. Several activities in this project focus on recruitment and retention of underrepresented students for long term careers in science. This project is jointly funded by the Division of Materials Research (DMR) and the Established Program to Stimulate Competitive Research (EPSCoR).Technical AbstractTerahertz (THz) time domain spectroscopy has led to a deeper understanding of the properties of matter and has become an invaluable tool in the study of low energy physics and dynamics in materials. The THz spectrum resides in a range of energies and timescales which are particularly important in materials with strong interactions. It would be highly advantageous to apply the technique to the emerging class of correlated two-dimensional, van der Waals heterostructures to characterize ground states and interactions which are currently not well understood. This project designs and optimizes a platform for THz spectroscopy of microscopic materials, at first focusing on 2D superconductors and magnets. Using planar waveguides and optically pumped photoconductive switches, the technique harnesses on-chip single cycle THz pulses to perform THz time domain spectroscopy of these materials, ushering in spectral information of low energy excitations and dynamics. The platform provides much needed insight on the possible pairing mechanisms in unconventional 2D superconductors and the relaxation dynamics of 2D magnets. It can also be readily applied to microscopic materials beyond investigations here and has broad application in routes to optimization of sub-diffraction THz spectroscopy and high frequency communications. This project is jointly funded by the Division of Materials Research (DMR) and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.