[Seminar] Lattice Vibrations in Chiral Materials: Bridging Condensed Matter Physics and Mechanical Engineering

Date

Thursday, February 27, 2025 - 14:00 to 15:00

Location

D23, Lab5 & Zoom

Description

Title:

Lattice Vibrations in Chiral Materials: Bridging
Condensed Matter Physics and Mechanical Engineering

Abstract:

 Chirality plays a pivotal role in materials science, yet traditional Cauchy-type elasticity theory fails to account for its effects. This limitation is addressed by micropolar elasticity theory [1], whose foundation can be traced back to Cosserat theory, which introduces rotational degrees of freedom by treating atomic clusters as rigid bodies.
 
. This framework uncovers the intricate coupling between translational and rotational motions in chiral crystals, resulting in phenomena such as band splitting in elastic wave dispersion and a novel low-frequency mode reminiscent of the "roton mode" in superfluid helium-4 [2]. 
This roton-like mode, a hybrid of rotational and translational motion, represents a new type of "chimera quasiparticle." Our theoretical predictions [2] have been experimentally verified using chiral metamaterials [3]. Further investigations from atomic lattice models have explored the interaction between electrons and chiral phonons [4].
This presentation begins by defining chirality [5] and its significance, followed by an introduction to the fundamental principles of chiral elastic waves and the role of micropolar elasticity theory. It concludes with a discussion of how these advancements open pathways for interdisciplinary research in condensed matter physics and mechanical engineering, offering perspectives on the dynamic properties of chiral materials.
 

[1] A.C. Eringen, Microcontinuum Field Theories: I. Foundations and Solids (Springer-Verlag, New York, 1999); W. Nowacki, Theory of Asymmetric Elasticity (Pergamon Press, Oxford, 1986).
[2] J. Kishine, A. S. Ovchinnikov, and A. A. Tereshchenko, "Chirality-Induced Phonon Dispersion in a Noncentrosymmetric Micropolar Crystal," Phys. Rev. Lett. 125, 245302 (2020).
[3] Y. Chen, M. Kadic, and M. Wegener, "Roton-like acoustical dispersion relations in 3D metamaterials," Nat. Commun. 12, 3278 (2021); Yi Chen et al., "Observation of chirality-induced roton-like dispersion in a 3D micropolar elastic metamaterial," Adv. Funct. Mater. 2302699 (2023).
[4] A. Kato and J. Kishine, "Note on angular momentum of phonons in chiral crystals," J. Phys. Soc. Jpn. 92, 075002 (2023).
[5] J. Kishine, H. Kusunose, and H. M. Yamamoto, "On the definition of chirality and enantioselective fields," Isr. J. Chem. 62, e202200049 (2022).

Bio

  Jun-ichiro Kishine received his Ph.D. in physics from the University of Tokyo in 1996. He served as an assistant professor at the Institute for Molecular Science from 1996 to 2003 and was a visiting scientist at the Massachusetts Institute of Technology from 2000 to 2001. In 2003, he joined Kyushu Institute of Technology as an associate professor, where he worked until 2012. Since then, he has been a professor of physics at the Open University of Japan. He has also held visiting professor positions at the Institute for Molecular Science (2019–2022), Kyoto University (2020–2022), and currently the University of Tokyo (2021–present). His research focuses on chiral symmetry breaking in materials and its physical consequences, primarily from the perspective of theoretical condensed matter physics.

Zoom:

Meeting URL: https://oist.zoom.us/j/91237544029?pwd=VU2vaaNMw0DzH9pCYsGhX6wmm9yPvY.1&from=addon

MeetingID: 912 3754 4029

Passcode: 022296

Attachments

Image icon Micropolar_and_Roton.jpg
All-OIST Category: 
Seminar

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