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Circular Phonon Dichroism in Weyl Semimetals
Donghao Liu1, Junren Shi1,2
1International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
Physical Review Letters
|September 27, 2017
Summary
We reveal how spin-orbit coupling in magnetic metals creates unique phonon behaviors. This leads to circular phonon dichroism, enabling control over phonon polarization in materials like Weyl semimetals.
Area of Science:
- Condensed matter physics
- Materials science
- Acoustics
Background:
- Phonon dynamics in magnetic materials are crucial for understanding thermal and transport properties.
- Spin-orbit coupling significantly influences electronic and magnetic properties, but its effect on phonon dynamics is less explored.
Purpose of the Study:
- To theoretically derive and analyze the phonon dynamics in magnetic metals with strong spin-orbit coupling.
- To investigate the emergence of circular phonon dichroism and its potential applications.
Main Methods:
- Derivation of phonon dynamics equations incorporating spin-orbit coupling.
- Analysis of phonon dispersion and damping in the presence of these interactions.
- Investigation of specific material systems, namely Weyl semimetals.
Main Results:
- Identified both dissipationless and dissipative viscosity terms in phonon dynamics.
- Demonstrated that these viscosities lead to the splitting and differential damping of circularly polarized phonons.
- Observed strong circular phonon dichroism in time-reversal and inversion symmetry-breaking Weyl semimetals.
Conclusions:
- Spin-orbit coupling provides a novel mechanism for controlling phonon polarization.
- Weyl semimetals exhibit significant circular phonon dichroism, making them promising for acoustic circular polarizer applications.
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