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Observation of chiral phonons
Hanyu Zhu1,2, Jun Yi1, Ming-Yang Li3
1Nanoscale Science and Engineering Center, University of California, Berkeley, CA 94720, USA.
Science (New York, N.Y.)
|February 9, 2018
Summary
Phonons, or quantized lattice vibrations, can exhibit intrinsic chirality in monolayer tungsten diselenide. This discovery, confirmed by infrared circular dichroism, opens new avenues for solid-state physics and information processing.
Area of Science:
- Condensed matter physics
- Quantum mechanics
- Materials science
Background:
- Chirality, a property of symmetry breaking, is fundamental in particle physics and observed in electron behavior in condensed matter.
- Unconventional transport phenomena, like the quantum Hall effect, are governed by electron chirality.
- Understanding phonon chirality is crucial for advancing solid-state phenomena.
Purpose of the Study:
- To demonstrate the existence of intrinsic chirality in phonons.
- To investigate the role of broken inversion symmetry in creating chiral phonons.
- To explore the implications of chiral phonons in materials like monolayer tungsten diselenide.
Main Methods:
- Utilizing indirect infrared absorption to identify phonons via hole-phonon interactions.
- Employing infrared circular dichroism to confirm phonon chirality.
- Analyzing the broken inversion symmetry in the tungsten diselenide lattice.
Main Results:
- Phonons in monolayer tungsten diselenide exhibit intrinsic chirality.
- The degeneracy of phonon modes is lifted due to broken lattice inversion symmetry.
- Chirality was confirmed through pseudoangular momentum conservation observed via circular dichroism.
Conclusions:
- Chiral phonons are a novel quantum phenomenon in condensed matter.
- This finding has significant implications for electron-phonon coupling and topological states in solids.
- Chiral phonons offer potential for energy-efficient information processing applications.
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