Observation of the axion quasiparticle in 2D MnBi2Te4

Jian-Xiang Qiu; Barun Ghosh; Jan Schütte-Engel; Tiema Qian; Michael Smith; Yueh-Ting Yao; Junyeong Ahn; Yu-Fei Liu; Anyuan Gao; Christian Tzschaschel; Houchen Li; Ioannis Petrides; Damien Bérubé; Thao Dinh; Tianye Huang; Olivia Liebman; Emily M. Been; Joanna M. Blawat; Kenji Watanabe; Takashi Taniguchi; Kin Chung Fong; Hsin Lin; Peter P. Orth; Prineha Narang; Claudia Felser; Tay-Rong Chang; Ross McDonald; Robert J. McQueeney; Arun Bansil; Ivar Martin; Ni Ni; Qiong Ma; David J. E. Marsh; Ashvin Vishwanath; Su-Yang Xu

doi:10.1038/s41586-025-08862-x

Observation of the axion quasiparticle in 2D MnBi2Te4

Jian-Xiang Qiu, Barun Ghosh, Jan Schütte-Engel, Tiema Qian, Michael Smith, Yueh-Ting Yao, Junyeong Ahn, Yu-Fei Liu, Anyuan Gao, Christian Tzschaschel, Houchen Li, Ioannis Petrides, Damien Bérubé, Thao Dinh, Tianye Huang, Olivia Liebman, Emily M. Been, Joanna M. Blawat, Kenji Watanabe, Takashi TaniguchiKin Chung Fong, Hsin Lin, Peter P. Orth, Prineha Narang, Claudia Felser, Tay-Rong Chang, Ross McDonald, Robert J. McQueeney, Arun Bansil, Ivar Martin, Ni Ni, Qiong Ma, David J. E. Marsh, Ashvin Vishwanath, Su-Yang Xu

Physics

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Abstract

The axion is a hypothetical fundamental particle that is conjectured to correspond to the coherent oscillation of the θ field in quantum chromodynamics. Its existence would solve multiple fundamental questions, including the strong CP problem of quantum chromodynamics and dark matter, but the axion has never been detected. Electrodynamics of condensed-matter systems can also give rise to a similar θ, so far studied as a static, quantized value to characterize the topology of materials3,4,5. Coherent oscillation of θ in condensed matter has been proposed to lead to physics directly analogous to the high-energy axion particle—the dynamical axion quasiparticle (DAQ). Here we report the observation of the DAQ in MnBi2Te4. By combining a two-dimensional electronic device with ultrafast pump–probe optics, we observe a coherent oscillation of θ at about 44 gigahertz, which is uniquely induced by its out-of-phase antiferromagnetic magnon. This represents direct evidence for the presence of the DAQ, which in two-dimensional MnBi2Te4 is found to arise from the magnon-induced coherent modulation of the Berry curvature. The DAQ also has implications in light–matter interaction and coherent antiferromagnetic spintronics, as it might lead to axion polaritons and electric control of ultrafast spin polarization. Finally, the DAQ could be used to detect axion particles. We estimate the detection frequency range and sensitivity in the millielectronvolt regime, which has so far been poorly explored.

Original language	English
Article number	84
Pages (from-to)	62-69
Number of pages	8
Journal	Nature
Volume	641
Issue number	8061
Early online date	16 Apr 2025
DOIs	https://doi.org/10.1038/s41586-025-08862-x
Publication status	Published - 1 May 2025

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Qiu, J.-X., Ghosh, B., Schütte-Engel, J., Qian, T., Smith, M., Yao, Y.-T., Ahn, J., Liu, Y.-F., Gao, A., Tzschaschel, C., Li, H., Petrides, I., Bérubé, D., Dinh, T., Huang, T., Liebman, O., Been, E. M., Blawat, J. M., Watanabe, K., ... Xu, S.-Y. (2025). Observation of the axion quasiparticle in 2D MnBi2Te4. Nature, 641(8061), 62-69. Article 84. https://doi.org/10.1038/s41586-025-08862-x

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title = "Observation of the axion quasiparticle in 2D MnBi2Te4",

abstract = "The axion is a hypothetical fundamental particle that is conjectured to correspond to the coherent oscillation of the θ field in quantum chromodynamics. Its existence would solve multiple fundamental questions, including the strong CP problem of quantum chromodynamics and dark matter, but the axion has never been detected. Electrodynamics of condensed-matter systems can also give rise to a similar θ, so far studied as a static, quantized value to characterize the topology of materials3,4,5. Coherent oscillation of θ in condensed matter has been proposed to lead to physics directly analogous to the high-energy axion particle—the dynamical axion quasiparticle (DAQ). Here we report the observation of the DAQ in MnBi2Te4. By combining a two-dimensional electronic device with ultrafast pump–probe optics, we observe a coherent oscillation of θ at about 44 gigahertz, which is uniquely induced by its out-of-phase antiferromagnetic magnon. This represents direct evidence for the presence of the DAQ, which in two-dimensional MnBi2Te4 is found to arise from the magnon-induced coherent modulation of the Berry curvature. The DAQ also has implications in light–matter interaction and coherent antiferromagnetic spintronics, as it might lead to axion polaritons and electric control of ultrafast spin polarization. Finally, the DAQ could be used to detect axion particles. We estimate the detection frequency range and sensitivity in the millielectronvolt regime, which has so far been poorly explored.",

author = "Jian-Xiang Qiu and Barun Ghosh and Jan Sch{\"u}tte-Engel and Tiema Qian and Michael Smith and Yueh-Ting Yao and Junyeong Ahn and Yu-Fei Liu and Anyuan Gao and Christian Tzschaschel and Houchen Li and Ioannis Petrides and Damien B{\'e}rub{\'e} and Thao Dinh and Tianye Huang and Olivia Liebman and Been, {Emily M.} and Blawat, {Joanna M.} and Kenji Watanabe and Takashi Taniguchi and Fong, {Kin Chung} and Hsin Lin and Orth, {Peter P.} and Prineha Narang and Claudia Felser and Tay-Rong Chang and Ross McDonald and McQueeney, {Robert J.} and Arun Bansil and Ivar Martin and Ni Ni and Qiong Ma and Marsh, {David J. E.} and Ashvin Vishwanath and Su-Yang Xu",

note = "Publisher Copyright: {\textcopyright} The Author(s), under exclusive licence to Springer Nature Limited 2025.",

year = "2025",

month = may,

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doi = "10.1038/s41586-025-08862-x",

language = "English",

volume = "641",

pages = "62--69",

journal = "Nature",

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Qiu, J-X, Ghosh, B, Schütte-Engel, J, Qian, T, Smith, M, Yao, Y-T, Ahn, J, Liu, Y-F, Gao, A, Tzschaschel, C, Li, H, Petrides, I, Bérubé, D, Dinh, T, Huang, T, Liebman, O, Been, EM, Blawat, JM, Watanabe, K, Taniguchi, T, Fong, KC, Lin, H, Orth, PP, Narang, P, Felser, C, Chang, T-R, McDonald, R, McQueeney, RJ, Bansil, A, Martin, I, Ni, N, Ma, Q, Marsh, DJE, Vishwanath, A & Xu, S-Y 2025, 'Observation of the axion quasiparticle in 2D MnBi2Te4', Nature, vol. 641, no. 8061, 84, pp. 62-69. https://doi.org/10.1038/s41586-025-08862-x

TY - JOUR

T1 - Observation of the axion quasiparticle in 2D MnBi2Te4

AU - Qiu, Jian-Xiang

AU - Ghosh, Barun

AU - Schütte-Engel, Jan

AU - Qian, Tiema

AU - Smith, Michael

AU - Yao, Yueh-Ting

AU - Ahn, Junyeong

AU - Liu, Yu-Fei

AU - Gao, Anyuan

AU - Tzschaschel, Christian

AU - Li, Houchen

AU - Petrides, Ioannis

AU - Bérubé, Damien

AU - Dinh, Thao

AU - Huang, Tianye

AU - Liebman, Olivia

AU - Been, Emily M.

AU - Blawat, Joanna M.

AU - Watanabe, Kenji

AU - Taniguchi, Takashi

AU - Fong, Kin Chung

AU - Lin, Hsin

AU - Orth, Peter P.

AU - Narang, Prineha

AU - Felser, Claudia

AU - Chang, Tay-Rong

AU - McDonald, Ross

AU - McQueeney, Robert J.

AU - Bansil, Arun

AU - Martin, Ivar

AU - Ni, Ni

AU - Ma, Qiong

AU - Marsh, David J. E.

AU - Vishwanath, Ashvin

AU - Xu, Su-Yang

PY - 2025/5/1

Y1 - 2025/5/1

N2 - The axion is a hypothetical fundamental particle that is conjectured to correspond to the coherent oscillation of the θ field in quantum chromodynamics. Its existence would solve multiple fundamental questions, including the strong CP problem of quantum chromodynamics and dark matter, but the axion has never been detected. Electrodynamics of condensed-matter systems can also give rise to a similar θ, so far studied as a static, quantized value to characterize the topology of materials3,4,5. Coherent oscillation of θ in condensed matter has been proposed to lead to physics directly analogous to the high-energy axion particle—the dynamical axion quasiparticle (DAQ). Here we report the observation of the DAQ in MnBi2Te4. By combining a two-dimensional electronic device with ultrafast pump–probe optics, we observe a coherent oscillation of θ at about 44 gigahertz, which is uniquely induced by its out-of-phase antiferromagnetic magnon. This represents direct evidence for the presence of the DAQ, which in two-dimensional MnBi2Te4 is found to arise from the magnon-induced coherent modulation of the Berry curvature. The DAQ also has implications in light–matter interaction and coherent antiferromagnetic spintronics, as it might lead to axion polaritons and electric control of ultrafast spin polarization. Finally, the DAQ could be used to detect axion particles. We estimate the detection frequency range and sensitivity in the millielectronvolt regime, which has so far been poorly explored.

AB - The axion is a hypothetical fundamental particle that is conjectured to correspond to the coherent oscillation of the θ field in quantum chromodynamics. Its existence would solve multiple fundamental questions, including the strong CP problem of quantum chromodynamics and dark matter, but the axion has never been detected. Electrodynamics of condensed-matter systems can also give rise to a similar θ, so far studied as a static, quantized value to characterize the topology of materials3,4,5. Coherent oscillation of θ in condensed matter has been proposed to lead to physics directly analogous to the high-energy axion particle—the dynamical axion quasiparticle (DAQ). Here we report the observation of the DAQ in MnBi2Te4. By combining a two-dimensional electronic device with ultrafast pump–probe optics, we observe a coherent oscillation of θ at about 44 gigahertz, which is uniquely induced by its out-of-phase antiferromagnetic magnon. This represents direct evidence for the presence of the DAQ, which in two-dimensional MnBi2Te4 is found to arise from the magnon-induced coherent modulation of the Berry curvature. The DAQ also has implications in light–matter interaction and coherent antiferromagnetic spintronics, as it might lead to axion polaritons and electric control of ultrafast spin polarization. Finally, the DAQ could be used to detect axion particles. We estimate the detection frequency range and sensitivity in the millielectronvolt regime, which has so far been poorly explored.

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U2 - 10.1038/s41586-025-08862-x

DO - 10.1038/s41586-025-08862-x

M3 - Article

SN - 0028-0836

VL - 641

SP - 62

EP - 69

JO - Nature

JF - Nature

IS - 8061

M1 - 84

ER -

Observation of the axion quasiparticle in 2D MnBi2Te4

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