ITS A QUANTUM UNIVERSE
Chiral phonons create orbital current via their own magnetism
In a new study, an international group of researchers has found that chiral phonons can create orbital current without needing magnetic elements – in part because chiral phonons have their own magnetic moments. Additionally, this effect can be achieved in common crystal materials. The work has potential for the development of less expensive, energy-efficient orbitronic devices for use in a wide array of electronics.
All electronic devices are based upon the charge of an electron, and electrons have three intrinsic properties: spin, charge and orbital angular momentum. While researchers have long explored the use of spin as a more efficient way to create current, the field of orbitronics – based upon using an electron’s orbital angular momentum, rather than its spin, to create a current flow – is still relatively new.
“Traditionally it has been technically challenging to generate orbital current,” says Dali Sun, co-corresponding author on the study. Sun is a professor of physics and member of the Organic and Carbon Electronics Lab (ORaCEL) at North Carolina State University.
“The generation of orbital currents traditionally necessitates the injection of charge current into specific transition metals, and many of these elements are now classified as critical materials – substances that the U.S. government identifies as essential to energy technologies, economic and national security, and the manufacture of key products. But this work shows that we can use a heat gradient to drive out chiral phonons in a quartz (i.e., SiO2) substrate, and the chiral phonons can be converted into orbital current.”
“There are other ways to generate orbital angular momentum, but this method allows for the use of cheaper, more abundant materials,” Sun says.
The new paper builds upon previous work that found spin current can be created and controlled by applying a thermal gradient to non-magnetic hybrid semiconductors that contain chiral phonons.
Chiral phonons are groups of atoms that move in a circular direction when excited by an energy source such as heat. As the phonons move through a material, they propagate that circular motion, or angular momentum, through it.
“In this work we show that we can use that angular momentum from the chiral phonon and convert it to orbital current instead of spin,” says Jun Liu, associate professor of mechanical and aerospace engineering at NC State and member of ORaCEL. “And we can do it in very simple non-magnetic insulators containing chiral phonons, because the rotation of the chiral phonon generates magnetism.” Liu is a co-corresponding author of the research.
The researchers hope that the work can pave the way toward cost-effective orbitronic applications.
“The work also answers fundamental questions around the interplay between structural chirality and orbital currents, which will hopefully help expand the field of orbitronics further,” Sun says.
The work appears in Nature Physics. Jun Zhou, a physicist at Nanjing Normal University, is a co-corresponding author. Yoji Nabei, a postdoc in Sun’s group, is the first author. Sun was supported in part by the Department of Energy under award number DE-SC0020992 and the Air Force Office of Scientific Research, Multidisciplinary University Research Initiatives (MURI) Program under award number FA9550-23-1-0311.
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Note to editors: An abstract follows.
“Orbital Seebeck effect induced by chiral phonons”
DOI: 10.1038/s41567-025-03134-x
Authors: Yoji Nabei, Cong Yang, Hana Jones, Andrew H. Comstock, Ziqi Wang, Benjamin Ewing, John Bingen, Rui Sun, Jun Liu, Dali Sun; North Carolina State University; Hong Sun, Jun Zhou, Nanjing Normal University; Thuc Mai, Rahul Rao, Air Force Research Laboratory; Tian Wang, Xiaosong Li, University of Washington; Rikard Bodin, Binod Pandey, Z.
Valy Vardeny, University of Utah; Yuzan Xiong, Wei Zhang, University of North Carolina at Chapel Hill; Dmitry Smirnov, National High Magnetic Field Laboratory; Axel Hoffmann, University of Illinois at Urbana-Champaign; Ming Hu, University of South Carolina; Binghai Yan, Pennsylvania State University
Published: Jan. 21, 2026 in Nature Physics
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 nonzero angular momentum due to the circular motion of the 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 promises for orbitronics based on chiral phonons in nonmagnetic insulators and shed light on the fundamental understanding of chiral phonons and their interaction with electron orbitals.
Journal
Nature Physics
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Orbital Seebeck effect induced by chiral phonons
Article Publication Date
21-Jan-2026
Using magnetic frustration to probe new quantum possibilities
UC Santa Barbara Professor Stephen Wilson’s lab group has established an innovative way to use a phenomenon referred to as frustration to engineer unconventional magnetic states with potential relevance for quantum technologies
image:
A researcher in the lab of Stephen Wilson, whose group studies how magnetic interactions can produce unusual states of matter relevant to quantum research.
view moreCredit: Matt Perko
Research in the lab of UC Santa Barbara materials professor Stephen Wilson is focused on understanding the fundamental physics behind unusual states of matter and developing materials that can host the kinds of properties needed for quantum functionalities.
In a paper published in the journal Nature Materials, Wilson’s lab group reports on an innovative way to use a phenomenon referred to as frustration of long-range order in a material system to engineer unconventional magnetic states with potential relevance for quantum technologies. At the same time, Wilson emphasized, “This is fundamental science aimed at addressing a basic question. It’s meant to probe what physics may be possible for future devices.”
The paper, “Interleaved bond frustration in a triangular lattice antiferromagnet,” explores how several types of frustration can come into play in this realm. One is geometric frustration, which refers to when the magnetic moments of a material are unable to settle in a single ordered arrangement, leaving them in a fluctuating state, or frustrated.
“You can think of magnetism as being derived from tiny bar magnets sitting at the atomic sites in a crystal lattice,” Wilson said. “Those bar magnets are what we call magnetic dipole moments, and they can interact and orient themselves relative to one another in specific ways, depending on the details of a material, to minimize their energy or, said another way, to realize their ground state.” That is the lowest energy state for any system, and any system at absolute zero temperature exists in its ground state.
“If those magnetic moments interact in a way that wants them to point antiparallel to one another, we call that antiferromagnetism,” Wilson added. “If they want to interact in this antiferromagnetic way, and if they are sitting on atoms forming a square network, then each moment can be antiparallel to its neighbors. The moments are ‘happy,’ and that is the ground state. In a different network, however, such as a triangle, not every moment can point opposite to its neighbors. They compete with one another, or are ‘frustrated,’ because they don’t know which way to point to realize the ground state of the system. The moments seek equilibrium but are frustrated from achieving it by the geometry of the space they occupy.”
It turns out that a similar type of frustration can occur with other aspects of the electron, its charge, for instance. In particular, if two neighboring ions try to share an electron across a bond, they can form what is called an atomic dimer. Similar to the case of antiferromagnetism, the formation of these dimers can be frustrated in certain lattice geometries, such as triangular lattices or honeycomb networks. What can then result is a frustrated bond network that is highly susceptible to strain, which can act to relieve the frustration of the bond network. Wilson’s paper examines an extremely rare system of materials where both of these types of frustration were found to coexist.
Wilson describes this advance as “exciting” because it opens a window into functional control over one frustrated system via a perturbation that impacts the other. Over the past six or seven years, researchers have found that they can engineer a frustrated magnetic state by using materials built from triangular networks of lanthanides, a group of elements located at the bottom of the periodic table.
“In principle, this triangular lattice network of properly chosen lanthanide moments can cause a special kind of intrinsically quantum disordered state to arise,” Wilson said. “One thing we tried to do in this project was to functionalize that exotic state by embedding it in a crystal lattice that has an additional degree of bond frustration.”
While there are many different “flavors” of quantum disordered magnetism, in principle, Wilson noted, “Some states can host long-range entanglement of spins, which is of interest in the realm of quantum information. Gaining control over those states via applying a strain in the frustrated bond network would be exciting.”
If you have two highly frustrated layers that are both very sensitive to perturbations, like strain, or, in the magnetic case, a magnetic field, then the question is whether you can couple the two together, because when one is biased and decides to order, it can potentially couple to the second one and alter it.
“It’s a way of imparting in things a functionality or response to other things to which it would otherwise not respond,” Wilson explained. “So, in principle, one can engineer large ferroic responses.You can apply a bit of strain, which induces magnetic order, or you can apply a bit of magnetic field and induce changes to the structure.
“Again, in principle, if you can find a quantum disordered ground state that hosts long-range entanglement, the question then becomes whether you can access that entanglement by, for instance, coupling to another layer, such as bond frustration.”
Wilson also wants to discover whether, through this process, it is possible to realize different types of intertwined order. “Basically, you could have different types of order that get nucleated because of the proximity of these two frustrated lattices,” he said. “That’s the big-picture idea.”
Journal
Nature Materials
Article Title
Interleaved bond frustration in a triangular lattice antiferromagnet
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