An illustration of chiral phonons, showing ions with angular momentum. Credit: R. Matthias Geilhufe, Chalmers

The rapidly growing field of research on chiral phonons is giving researchers new insights into the fundamental behaviors and structures of materials. The chirality of phonons could pave the way for new methods to control material properties and to encode information at the quantum level, which has implications for, among other areas, quantum technologies, electronics, energy transport, and sensor technology.

A recently published perpsective article in Nature Physics describes the development of this emerging research area, presents a framework for the classification of phonons, and provides a comprehensive overview of the materials in which chiral phonons have been studied or may be discovered in the future. This work is helping accelerate progress in one of today’s fastest-growing areas of quantum materials.

Matthias Geilhufe, Assistant Professor at the Department of Physics, conducts research on chiral phonons and is one of the main authors of the article.

What are chiral phonons and where and when do they occur? How do they arise?

The materials around us are composed of an enormous number of ions and electrons. Often, these ions are arranged in a regular structure called a crystal lattice. In such a crystal lattice, ions are organized in the form of a regular grid. However, ions don’t remain still in their lattice positions. Since ions interact with each other, their motion can be described as waves. These waves of lattice excitations can be described using quantum mechanics and are called phonons.

Chirality is a basic concept of nature, referring to objects that cannot be superimposed onto their mirror image. A classic example is our hands: the right hand is the mirror image of the left, but they cannot be aligned perfectly. In chemistry, the mirror-image forms of a molecule are called enantiomers. Chiral phonons are lattice excitations where two distinct enantiomers exist. They can arise naturally due to crystal symmetry or can be excited using laser fields.

What could knowledge about chiral phonons lead to in the future?

The symmetry of chiral phonons allows them to couple with a material’s magnetization or applied magnetic fields. Over the past five years, various experiments have been developed showing that this coupling is significantly stronger than previously thought. Some chiral phonons possess angular momentum, which introduces an effective magnetic field.

For example, this field has been shown to be strong enough to control a material’s magnetization—a crucial requirement for future information storage in computers. Notably, generating an effective magnetic field using chiral phonons requires much less energy compared to conventional magnetic fields.

Even chiral phonons without angular momentum—so-called geometric chiral phonons—have been shown to couple with electron spin through an effect called CISS (Chirality-Induced Spin Selectivity). The CISS effect is also important in chemistry, where molecular properties can depend heavily on the type of enantiomer. If we can control geometric chiral phonons, it may be possible to develop catalysts that distinguish between two enantiomers using laser fields.

What do you find most interesting about chiral phonons?

Together with my research group at Chalmers University of Technology, we have developed theoretical models explaining how chiral phonons can lead to strong coupling with magnetization. I believe this effect could not only be used for new technologies but also help explain certain phase transitions in materials that have remained poorly understood today. We are particularly interested in the role of chiral phonons in many-body systems and generalizations of chiral phonons, such as in rotating systems.

More information: Dominik M. Juraschek et al, Chiral phonons, Nature Physics (2025). DOI: 10.1038/s41567-025-03001-9

Citation: Q&A: Chiral phonons research offers new ways to control materials (2025, November 11) retrieved 11 November 2025 from https://phys.org/news/2025-11-qa-chiral-phonons-ways-materials.html

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