PHAS Colloquia

Raman spectroscopy of van der Waals magnet CrI3

by Rui He (Texas Tech University)

Tuesday, 9 March 2021 from to (America/Chicago)
Description
Speaker: Dr. Rui He (ECE, Texas Tech University)

Title: Raman spectroscopy of van der Waals magnet CrI3

Abstract: Van der Waals (or 2D) materials with intrinsic ferromagnetism have attracted massive interest because of their potential applications in data storage and spintronics devices. Atomic layers of chromium triiodide (CrI3) are one of such 2D ferromagnetic (FM) materials that have been demonstrated to realize long range FM order in its monolayer limit. In this talk, I will present our recent Raman spectroscopy studies of magnons (spin waves) and magnetism-induced phonons in bulk and thin layers of CrI3. Using magnetic field- and temperature-dependent ultralow frequency Raman spectroscopy, we reveal a novel mixed state of layered antiferromagnetism (AFM) and FM in 3D CrI3 bulk crystals where the layered AFM survives in the surface layers and the FM appears in deeper bulk layers. In thin layers (1-4 layers) of CrI3, we use a combination of polarized Raman spectroscopy experiment and magnetism-phonon coupling calculation to study the rich magneto-Raman effect. Our results explain why a van der Waals magnet may show different magnetic behaviors in its layered and bulk forms and reveal the spin-phonon coupling physics in its atomic layers.

About the speaker: Dr. Rui He obtained her B.S. degree from Fudan University in China in 1999. She received her Ph.D. degree in Applied Physics from Columbia University in the City of New York in 2006. After her graduation from Columbia, she joined the Hong Kong University of Science and Technology as a postdoc in the Physics Department. In 2009 she returned to Columbia University where she worked as a postdoctoral research scientist. She joined the Physics Department at the University of Northern Iowa as an assistant professor in August 2011 and became an associate professor in 2016. She joined the Electrical and Computer Engineering Department at Texas Tech University as an associate professor in July 2017. She is an NSF CAREER award recipient, and her research interests include the general area of Raman studies of nanostructures, especially 2D materials and their heterostructures.

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Join Zoom Meeting by clicking the link in the material below or
https://zoom.us/j/9952917599?pwd=MHdiOFRIRG1kVFJ2a1JjVXczVEVnUT09

Meeting ID: 995 291 7599
Passcode: PHAS

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Please also visit Department Colloquia webpage. Please find the link below more information.

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Material
Organised by Sung-Won Lee, Myoung-Hwan Kim/ CMP