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Conference Paper: Experimental observation of chiral phonons in monolayer WSe2

TitleExperimental observation of chiral phonons in monolayer WSe<inf>2</inf>
Authors
KeywordsZone-boundary
Chirality
Intervalence band transition
Time-reversal symmetry breaking
Phonon
Valley
Indirect absorption
Transition metal dichalcogenide
Issue Date2019
Citation
Proceedings of SPIE - The International Society for Optical Engineering, 2019, v. 10916, article no. 109160C How to Cite?
AbstractChirality characterizes an object that is not identical to its mirror image. In condensed matter physics, Fermions have been demonstrated to obtain chirality through structural and time-reversal symmetry breaking. These systems display unconventional electronic transport phenomena such as the quantum Hall effect and Weyl semimetals. However, for bosonic collective excitations in atomic lattices, chirality was only theoretically predicted and has never been observed. We experimentally show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide, whose lattice breaks the inversion symmetry and enables inequivalent electronic K and -K valley states. The time-reversal symmetry is also broken when we selectively excite the valley polarized holes by circularly polarized light. Brillouin-zone-boundary phonons are then optically created by the indirect infrared absorption through the hole-phonon interactions. The unidirectional intervalley transfer of holes ensures that only the phonon modes in one valley are excited. We found that such photons are chiral through the transient infrared circular dichroism, which proves the valley phonons responsible to the indirect absorption has non-zero pseudo-angular momentum. From the spectrum we further deduce the energy transferred to the phonons that agrees with both the first principle calculation and the double-resonance Raman spectroscopy. The chiral phonons have significant implications for electron-phonon coupling in solids, lattice-driven topological states, and energy efficient information processing.
Persistent Identifierhttp://hdl.handle.net/10722/298308
ISSN
2020 SCImago Journal Rankings: 0.192

 

DC FieldValueLanguage
dc.contributor.authorZhu, Hanyu-
dc.contributor.authorYi, Jun-
dc.contributor.authorLi, Ming Yang-
dc.contributor.authorXiao, Jun-
dc.contributor.authorZhang, Lifa-
dc.contributor.authorYang, Chih Wen-
dc.contributor.authorYang, Sui-
dc.contributor.authorKaindl, Robert A.-
dc.contributor.authorLi, Lain Jong-
dc.contributor.authorWang, Yuan-
dc.contributor.authorZhang, Xiang-
dc.date.accessioned2021-04-08T03:08:07Z-
dc.date.available2021-04-08T03:08:07Z-
dc.date.issued2019-
dc.identifier.citationProceedings of SPIE - The International Society for Optical Engineering, 2019, v. 10916, article no. 109160C-
dc.identifier.issn0277-786X-
dc.identifier.urihttp://hdl.handle.net/10722/298308-
dc.description.abstractChirality characterizes an object that is not identical to its mirror image. In condensed matter physics, Fermions have been demonstrated to obtain chirality through structural and time-reversal symmetry breaking. These systems display unconventional electronic transport phenomena such as the quantum Hall effect and Weyl semimetals. However, for bosonic collective excitations in atomic lattices, chirality was only theoretically predicted and has never been observed. We experimentally show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide, whose lattice breaks the inversion symmetry and enables inequivalent electronic K and -K valley states. The time-reversal symmetry is also broken when we selectively excite the valley polarized holes by circularly polarized light. Brillouin-zone-boundary phonons are then optically created by the indirect infrared absorption through the hole-phonon interactions. The unidirectional intervalley transfer of holes ensures that only the phonon modes in one valley are excited. We found that such photons are chiral through the transient infrared circular dichroism, which proves the valley phonons responsible to the indirect absorption has non-zero pseudo-angular momentum. From the spectrum we further deduce the energy transferred to the phonons that agrees with both the first principle calculation and the double-resonance Raman spectroscopy. The chiral phonons have significant implications for electron-phonon coupling in solids, lattice-driven topological states, and energy efficient information processing.-
dc.languageeng-
dc.relation.ispartofProceedings of SPIE - The International Society for Optical Engineering-
dc.subjectZone-boundary-
dc.subjectChirality-
dc.subjectIntervalence band transition-
dc.subjectTime-reversal symmetry breaking-
dc.subjectPhonon-
dc.subjectValley-
dc.subjectIndirect absorption-
dc.subjectTransition metal dichalcogenide-
dc.titleExperimental observation of chiral phonons in monolayer WSe<inf>2</inf>-
dc.typeConference_Paper-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1117/12.2510760-
dc.identifier.scopuseid_2-s2.0-85066023720-
dc.identifier.volume10916-
dc.identifier.spagearticle no. 109160C-
dc.identifier.epagearticle no. 109160C-
dc.identifier.eissn1996-756X-
dc.identifier.issnl0277-786X-

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