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DOE OSTI · 2573558

Measurement of phonon angular momentum

Zhang, Heda [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000188646671)·Peshcherenko, Nikolai [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)]·Yang, Fazhi [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000327889279)·Ward, T. Zac [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000210279186)·Raghuvanshi, Parul Rani [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000223254324)·Lindsay, Lucas [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000196457993)·Felser, Claudia [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)] (ORCID:0000000282002063)·Zhang, Yang [Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0000000346305056)·Yan, Jiaqiang -Q. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000166254706)·Miao, Hu [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000310785713)
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Abstract

In condensed matter, angular momentum is intimately related to the emergence of topological quantum states, including chiral superconductivity, quantum spin liquids and various chiral quasiparticles. Recently, it has been predicted that microscopic lattice excitations, known as phonons, can carry finite angular momentum, leading to specific physical properties of materials. However, phonon angular momentum has not yet been observed directly. Here, in this study, we demonstrate that angular momentum conservation results in a macroscopic mechanical torque when applying a time-reversal symmetry-breaking thermal gradient along the chiral axis of single-crystal tellurium. We probe this torque using a cantilever-based device and establish that it changes sign by flipping the chirality or thermal gradient. This behavior disappears in polycrystalline samples that lack a preferred chirality. Our experimental results align well with theoretical calculations. We provide compelling evidence for phonon angular momentum, which might enable quantum states with potential applications in microelectronics.

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36 MATERIALS SCIENCE

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Zhang, Heda [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000188646671), Peshcherenko, Nikolai [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)], Yang, Fazhi [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000327889279), Ward, T. Zac [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000210279186), Raghuvanshi, Parul Rani [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000223254324), Lindsay, Lucas [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000196457993), Felser, Claudia [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany)] (ORCID:0000000282002063), Zhang, Yang [Univ. of Tennessee, Knoxville, TN (United States)] (ORCID:0000000346305056), Yan, Jiaqiang -Q. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000166254706), Miao, Hu [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000310785713). 2025-07-11. Measurement of phonon angular momentum. https://doi.org/10.1038/s41567-025-02952-3

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