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Zhe Fei, assistant professor of physics, received an NSF CAREER grant for a proposal titled “Exploring chiral edge plasmons in novel two-dimensional materials.”

The estimated total award amount is $588,818.

Abstract at Time of Award
Nontechnical Description: The capability of controlling the flow of light in the nanoscale is extremely important for realizing functioning optical circuitry for fast data processing and broadband signal communications. Nevertheless, unlike electronic signals, it is challenging to control optical signals in the nanoscale. This project explores a class of novel materials with atomic thicknesses, where a special type of light with nanoscale footprints can travel at the edges of these materials. Moreover, both the direction and the intensity of the “nanoscale light” are actively controlled, and only one-way transport is allowed under certain conditions. The main goal of this research is to uncover the general characteristics and key functionalities of these “nanoscale light”, which could pave the way for its applications in next-generation computers. This project provides opportunities for mentoring and training high-school, undergraduate and graduate students, especially those from unrepresentative minorities in science and engineering. In addition, the project team offers special outreaching activities in the themes of two-dimensional materials or optics for the public and designs new teaching materials for advanced lab courses at Iowa State University.

Technical Description: The project team aims to realize the ultimate control of nanophotonic signals by exploring chiral edge plasmons in novel two-dimensional materials. These edge modes are formed by the coupling between photons and electrons in the atomically-thin samples and can propagate strictly along the sample edges. The chirality is introduced either by applying a magnetic field or inducing net Bloch band Berry curvature with optical excitations. State-of-the-art scattering-type scanning near-field optical microscopy will provide ultrafast, ultrasmall and broadband imaging and spectroscopy of chiral edge plasmons at cryogenic temperatures and high magnetic field. With this technique, the project team plans to perform systematic studies of chiral plasmons in the benchmark two-dimensional materials – graphene and group six transition-metal dichalcogenides. The main objectives include characterizing the general properties of chiral plasmons and demonstrating the basic functionalities of these modes related to nanoscale signal control. The research is expected to deepen our understanding of the intriguing nano-optical physics in association with electron-electron interactions and Berry curvature in two-dimensional materials, revolutionize our approach towards tunable chiral plasmonics in the technologically important terahertz to infrared regions, and establish chiral edge plasmons as novel media for nonreciprocal signal communications with broad bandwidth and active tunability.

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.