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.
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Acknowledgements
D. Sun acknowledges primary financial support from the Department of Energy under award number DE-SC0020992. D. Sun, J.L., X.L. and A.H. acknowledge the Air Force Office of Scientific Research, Multidisciplinary University Research Initiatives (MURI) Program, under award number FA9550-23-1-0311 for the phonon calculation, modelling work and interpretations. Device fabrication at NC State was partially supported by the National Science Foundation (NSF) under award number DMR-2143642. Y.X. and W.Z. acknowledges US NSF under grant number DMR-2509513 for sample preparation assistance. B.Y. acknowledges financial support from the Israel Science Foundation (ISF: 2974/23) and from the Penn State Materials Research Science and Engineering Center for Nanoscale Science from the NSF under award number DMR-2011839. M.H. acknowledges financial support from NSF under grant numbers OAC-2311202 and CNS-2320292. T.M. and R.R. acknowledge funding from Air Force Office of Scientific Research grant number LRIR 23RXCOR003. Z.V.V. acknowledges funding from Air Force Office of Scientific Research grant number 23RT0542 for Raman measurements. The magneto-Raman measurements supported by the US Department of Energy (DE-FG02-07ER46451) were performed at the National High Magnetic Field Laboratory, which is supported by the NSF Cooperative Agreement No. DMR-2128556 and the State of Florida. J.L. acknowledges financial support from the NSF under award number CBET-1943813 for the simulation work done by Z.W.
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Y.N., D. Sun, J.L. and J.Z. conceived the experiment and supervised this research. Y.N. was responsible for the magnetotransport measurements. Y.N., W.Z., Y.X., H.J., B.E., J.B. and R.S. fabricated the samples. T.M. and R.R. performed the polarization-dependent Raman measurements. H.S., J.Z., Y.N., X.L., A.H.C., A.H. and B.Y. provided theoretical interpretations. T.W. and X.L. conducted the vibrational circular dichroism calculation. C.Y., H.S. and M.H. conducted the density functional theory calculation and analysis. Z.W. conducted a transient heat conduction simulation under J.L.’s supervision. R.B. and B.P. performed circular-polarization-resolved magneto-Raman spectroscopy under D. Smirnov and Z.V.V’s supervision. Y.N. and D. Sun wrote the manuscript. All authors contributed to editing the manuscript.
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Nabei, Y., Yang, C., Sun, H. et al. Orbital Seebeck effect induced by chiral phonons. Nat. Phys. 22, 245–251 (2026). https://doi.org/10.1038/s41567-025-03134-x
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DOI: https://doi.org/10.1038/s41567-025-03134-x
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