Observation of chiral phonons

Hanyu Zhu, Jun Yi, Ming-yang Li, Jun Xiao, Lifa Zhang, Chih-Wen Yang, Robert A. Kaindl, Lain-Jong Li, Yuan Wang, Xiang Zhang

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of clockwise and counterclockwise phonon modes at the corners of the Brillouin zone. We identified the phonons by the intervalley transfer of holes through hole-phonon interactions during the indirect infrared absorption, and we confirmed their chirality by the infrared circular dichroism arising from pseudoangular momentum conservation. The chiral phonons are important for electron-phonon coupling in solids, phonon-driven topological states, and energy-efficient information processing.
Original languageEnglish (US)
Pages (from-to)579-582
Number of pages4
JournalScience
Volume359
Issue number6375
DOIs
StatePublished - Feb 1 2018

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