Boosting chiral phonons via magnetic chirality

Jun Okamoto^1*, Chung-Yu Mou², Hsiao-Yu Huang¹, Ganesha Channagowdra¹, Choonjae Won³, Kai Du⁴, Xiaochen Feng⁴, Evgenia Komleva^5,6, Chien-Te Chen¹, Sergey Streltsov^5,6, Atsushi Fujimori^1,2,7, Sang-Wook Cheong⁴, Di-Jing Huang^1,8,9

¹National Synchrotron Radiation Research Center, Hsinchu, Taiwan
²Center for Quantum Science and Technology and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
³Max Plank POSTECH, Pohang, Korea
⁴Rutgers Center for Emergent Materials and Department Physics and Astronomy, Rutgers University, New Jersey, USA
⁵Institute of Metal Physics, Ekaterinburg, Russian Federation
⁶Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Ekateringburg, Russian Federation
⁷Department of Physics, University of Tokyo, Tokyo, Japan
⁸Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
⁹Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Jun Okamoto, email:okamoto.jun@nsrrc.org.tw

Chiral phonons, lattice vibration modes in solids that involve atoms rotating perpendicularly to their propagation, have recently attracted interest with their coupling to novel collective phenomena through angular momentum. For experimental verification of chiral phonons, resonant inelastic X-ray scattering (RIXS) with circularly polarized X-rays is one of the powerful methods, such as chiral phonons in α-quartz [1]. In condensed physics, coupling of chiral phonon and magnetization is one of the hot topics.
We present the O K-edge RIXS measurements demonstrating that giant chiral phonons are induced by helical spins in Mn-doped Ni₃TeO₆, a chiral and polar multiferroic [2]. The phonon excitations probed by RIXS with circularly polarized X-rays show pronounced circular dichroism in the helical spin phase, resulting from the antisymmetric exchange interaction, i.e., the Dzyaloshinskii-Moriya interaction, between neighboring non-collinear spins. Our findings highlight the connection between phonon motion and induced magnetization.

References
[1] H. Ueda et al., Nature 618, 946 (2024).
[2] J. Kim et al., Phys. Rev. Mater. 5, 094405 (2021).

Keywords: chiral phonon, chirality, helical antiferromagnetism, Resonant Inelastic X-ray Scattering