Observation of the Axion quasiparticle in 2D MnBi$_2$Te$_4$

Fuente: arXiv
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Autori principali: Qiu, Jian-Xiang, Ghosh, Barun, Schütte-Engel, Jan, Qian, Tiema, Smith, Michael, Yao, Yueh-Ting, Ahn, Junyeong, Liu, Yu-Fei, Gao, Anyuan, Tzschaschel, Christian, Li, Houchen, Petrides, Ioannis, Bérubé, Damien, Dinh, Thao, Huang, Tianye, Liebman, Olivia, Been, Emily M., Blawat, Joanna M., Watanabe, Kenji, Taniguchi, Takashi, Fong, Kin Chung, Lin, Hsin, Orth, Peter P., Narang, Prineha, Felser, Claudia, Chang, Tay-Rong, McDonald, Ross, McQueeney, Robert J., Bansil, Arun, Martin, Ivar, Ni, Ni, Ma, Qiong, Marsh, David J. E., Vishwanath, Ashvin, Xu, Su-Yang
Natura: Preprint
Pubblicazione: 2025
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author Qiu, Jian-Xiang
Ghosh, Barun
Schütte-Engel, Jan
Qian, Tiema
Smith, Michael
Yao, Yueh-Ting
Ahn, Junyeong
Liu, Yu-Fei
Gao, Anyuan
Tzschaschel, Christian
Li, Houchen
Petrides, Ioannis
Bérubé, Damien
Dinh, Thao
Huang, Tianye
Liebman, Olivia
Been, Emily M.
Blawat, Joanna M.
Watanabe, Kenji
Taniguchi, Takashi
Fong, Kin Chung
Lin, Hsin
Orth, Peter P.
Narang, Prineha
Felser, Claudia
Chang, Tay-Rong
McDonald, Ross
McQueeney, Robert J.
Bansil, Arun
Martin, Ivar
Ni, Ni
Ma, Qiong
Marsh, David J. E.
Vishwanath, Ashvin
Xu, Su-Yang
author_facet Qiu, Jian-Xiang
Ghosh, Barun
Schütte-Engel, Jan
Qian, Tiema
Smith, Michael
Yao, Yueh-Ting
Ahn, Junyeong
Liu, Yu-Fei
Gao, Anyuan
Tzschaschel, Christian
Li, Houchen
Petrides, Ioannis
Bérubé, Damien
Dinh, Thao
Huang, Tianye
Liebman, Olivia
Been, Emily M.
Blawat, Joanna M.
Watanabe, Kenji
Taniguchi, Takashi
Fong, Kin Chung
Lin, Hsin
Orth, Peter P.
Narang, Prineha
Felser, Claudia
Chang, Tay-Rong
McDonald, Ross
McQueeney, Robert J.
Bansil, Arun
Martin, Ivar
Ni, Ni
Ma, Qiong
Marsh, David J. E.
Vishwanath, Ashvin
Xu, Su-Yang
contents In 1978, Wilczek and Weinberg theoretically discovered a new boson-the Axion-which is the coherent oscillation of the $θ$ field in QCD. Its existence can solve multiple fundamental questions including the strong CP problem of QCD and the dark matter. However, its detection is challenging because it has almost no interaction with existing particles. Similar $θ$ has been introduced to condensed matter and so far studied as a static, quantized value to characterize topology of materials. But the coherent oscillation of $θ$ in condensed matter is proposed to lead to new physics directly analogous to the high-energy Axion particle, the dynamical Axion quasiparticle (DAQ). In this paper, we present the direct observation of the DAQ. By combining 2D electronic device with ultrafast pump-probe optics, we manage to measure the magnetoelectric coupling $θ$ ($θ\proptoα$) of 2D MnBi$_2$Te$_4$ with sub-picosecond time-resolution. This allows us to directly observe the DAQ by seeing a coherent oscillation of $θ$ at ~44 GHz in real time, which is uniquely induced by the out-of-phase antiferromagnetic magnon. Interestingly, in 2D MnBi$_2$Te$_4$, the DAQ arises from the magnon-induced coherent modulation of Berry curvature. Such ultrafast control of quantum wavefunction can be generalized to manipulate Berry curvature and quantum metric of other materials in ultrafast time-scale. Moreover, the DAQ enables novel quantum physics such as Axion polariton and electric control of ultrafast spin polarization, implying applications in unconventional light-matter interaction and coherent antiferromagnetic spintronics. Beyond condensed matter, the DAQ can serve as a detector of the dark matter Axion particle. We estimate the detection frequency range and sensitivity in the critically-lacking meV regime, contributing to one of the most challenging questions in fundamental physics.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12572
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of the Axion quasiparticle in 2D MnBi$_2$Te$_4$
Qiu, Jian-Xiang
Ghosh, Barun
Schütte-Engel, Jan
Qian, Tiema
Smith, Michael
Yao, Yueh-Ting
Ahn, Junyeong
Liu, Yu-Fei
Gao, Anyuan
Tzschaschel, Christian
Li, Houchen
Petrides, Ioannis
Bérubé, Damien
Dinh, Thao
Huang, Tianye
Liebman, Olivia
Been, Emily M.
Blawat, Joanna M.
Watanabe, Kenji
Taniguchi, Takashi
Fong, Kin Chung
Lin, Hsin
Orth, Peter P.
Narang, Prineha
Felser, Claudia
Chang, Tay-Rong
McDonald, Ross
McQueeney, Robert J.
Bansil, Arun
Martin, Ivar
Ni, Ni
Ma, Qiong
Marsh, David J. E.
Vishwanath, Ashvin
Xu, Su-Yang
Mesoscale and Nanoscale Physics
Materials Science
In 1978, Wilczek and Weinberg theoretically discovered a new boson-the Axion-which is the coherent oscillation of the $θ$ field in QCD. Its existence can solve multiple fundamental questions including the strong CP problem of QCD and the dark matter. However, its detection is challenging because it has almost no interaction with existing particles. Similar $θ$ has been introduced to condensed matter and so far studied as a static, quantized value to characterize topology of materials. But the coherent oscillation of $θ$ in condensed matter is proposed to lead to new physics directly analogous to the high-energy Axion particle, the dynamical Axion quasiparticle (DAQ). In this paper, we present the direct observation of the DAQ. By combining 2D electronic device with ultrafast pump-probe optics, we manage to measure the magnetoelectric coupling $θ$ ($θ\proptoα$) of 2D MnBi$_2$Te$_4$ with sub-picosecond time-resolution. This allows us to directly observe the DAQ by seeing a coherent oscillation of $θ$ at ~44 GHz in real time, which is uniquely induced by the out-of-phase antiferromagnetic magnon. Interestingly, in 2D MnBi$_2$Te$_4$, the DAQ arises from the magnon-induced coherent modulation of Berry curvature. Such ultrafast control of quantum wavefunction can be generalized to manipulate Berry curvature and quantum metric of other materials in ultrafast time-scale. Moreover, the DAQ enables novel quantum physics such as Axion polariton and electric control of ultrafast spin polarization, implying applications in unconventional light-matter interaction and coherent antiferromagnetic spintronics. Beyond condensed matter, the DAQ can serve as a detector of the dark matter Axion particle. We estimate the detection frequency range and sensitivity in the critically-lacking meV regime, contributing to one of the most challenging questions in fundamental physics.
title Observation of the Axion quasiparticle in 2D MnBi$_2$Te$_4$
topic Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2504.12572