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Canceled: Duke Physics Colloquium: Topological Aspects of Electromagnetic Response in Metals

Joel Moore
**CANCELED**
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Wednesday, April 22, 2020
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3:30 pm - 4:30 pm
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Joel Moore (UC Berkeley and Lawrence Berkeley National Laboratory)
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Duke Physics Colloquium

** This event had been canceled. **

"Topological Aspects of Electromagnetic Response in Metals"

This talk begins with an introduction to how topological phases of electrons can generate quantized responses and emergent particles such as Weyl fermions. Various insulating topological phases are known to realize unique electromagnetic couplings such as the quantum Hall effect and "axion electrodynamics", and understanding this led to an improved understanding of polarization and magnetoelectricity in all materials. The main new results are on how the recently discovered topological Weyl and Dirac semimetals can show unique electromagnetic responses. We argue that in linear response the main observable effect solves an old problem via the orbital moment of Bloch electrons, and how in nonlinear optics there should be a novel approximately quantized photocurrent effect. This photocurrent effect should have magnitude determined by fundamental constants, namely the cube of electric charge, divided by the square of Planck's constant, and may have been observed in recent experiments.

Faculty host: Thomas Barthel

Refreshments will be available before the event in room 130.

Contact: Cristin Paul