Spin, Charge, and Phonon Coupling Effects in 2D Materials

Max Planck Lecture on Non-Equilibrium Quantum Phenomena

  • Date: Mar 24, 2021
  • Time: 16:00 - 17:00
  • Speaker: Xiaodong Xu
  • University of Washington
  • Location: online via Zoom
  • Host: Andrea Cavalleri, Angel Rubio
Spin, Charge, and Phonon Coupling Effects in 2D Materials

Abstract:

The coupling between spin, charge, and lattice degrees of freedom plays an important role in a wide range of fundamental phenomena. 2D material is an emerging platform for studying these coupling effects. In this talk, I will present a couple examples along this direction. I will firstly discuss the observation of antiferromagnetic exciton and multiple exciton phonon bound states in zigzag antiferromagnet NiPS3. I will then present the observation of valley phonons, i.e. phonons with momentum vectors pointing to the corners of Brillouin zone, and their interaction with spins in a monolayer semiconductor WSe2. We identified the efficient intervalley scattering of quasi particles in both exciton formation and light emission process. These understandings enable us to unravel a series of photoluminescence peaks as valley phonon replicas of neutral and charged dark excitons.

Bio:

Xiaodong Xu is a Boeing Distinguished Professor in the Department of Physics and the Department of Materials Science and Engineering at the University of Washington. He received his PhD (Physics, 2008) from the University of Michigan and then performed postdoctoral research (2009-2010) at the Center for Nanoscale Systems at Cornell University. His nanoscale quantum-optoelectronics group at University of Washington focuses on creation, control, and understanding of novel device physics based on low-dimensional quantum materials.


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