キラルフォノンが独自の磁性で軌道電流を生成(Chiral Phonons Create Orbital Current via Their Own Magnetism)

2026-01-21 ノースカロライナ州立大学(NC State)

北カロライナ州立大学(NC State University)などの国際研究チームは、キラルフォノン(chiral phonons)が独自の磁気モーメントを持つことで、磁性材料なしに電子の軌道電流(orbital current)を生成できることを実証した。この現象は、熱勾配をかけた一般的な結晶材料(例:石英・SiO₂)内でキラルフォノンが発生し、その回転運動が軌道角運動量として伝播することで起きる。従来、軌道電流はスピンや磁性材料を用いる必要があったが、この方法によりより安価でエネルギー効率の高いオービトロニクス(orbitronics)デバイスの開発が期待される。研究成果は『Nature Physics』に掲載されており、逆オービタルホール効果を用いた検出実験でも実証された。さらに、構造のキラリティと軌道電流生成の基本的メカニズム解明にも寄与するという。

キラルフォノンが独自の磁性で軌道電流を生成(Chiral Phonons Create Orbital Current via Their Own Magnetism)
A quartz crystal subjected to a temperature gradient, leading to the generation of orbital angular momentum in the surrounding electron environment. Image: NC State University

<関連情報>

カイラルフォノンによって誘起される軌道ゼーベック効果 Orbital Seebeck effect induced by chiral phonons

Yoji Nabei,Cong Yang,Hong Sun,Hana Jones,Thuc Mai,Tian Wang,Rikard Bodin,Binod Pandey,Ziqi Wang,Yuzan Xiong,Andrew H. Comstock,Benjamin Ewing,John Bingen,Rui Sun,Dmitry Smirnov,Wei Zhang,Axel Hoffmann,Rahul Rao,Ming Hu,Z. Valy Vardeny,Binghai Yan,Xiaosong Li,Jun Zhou,Jun Liu & Dali Sun
Nature Physics  Published:21 January 2026
DOI:https://doi.org/10.1038/s41567-025-03134-x

Abstract

The orbital angular momentum of electrons presents exciting opportunities for developing energy-efficient, low-power magnetic devices. Typically, the generation of orbital currents is driven by the transfer of orbital angular momentum from 3d transition metal magnets, either through the application of an electric field using the orbital Hall effect or through magnetization dynamics. Chiral phonons are quantized lattice vibrations that carry non-zero angular momentum due to the circular motion of atoms. An interplay of chiral phonon dynamics and electrons would enable the direct generation of orbital angular momentum, even without the need for magnetic elements. Here we experimentally demonstrate the generation of orbital currents from chiral phonons activated in the chiral insulator α-quartz under an applied magnetic field and a temperature gradient. We refer to this phenomenon as the orbital Seebeck effect. The generated orbital current is selectively detected in tungsten and titanium films deposited on quartz through the inverse orbital Hall effect. Our findings hold promise for orbitronics based on chiral phonons in non-magnetic insulators and shed light on the fundamental understanding of chiral phonons and their interaction with electron orbitals.

1701物理及び化学
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