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| Format: | Preprint |
| Published: |
2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2411.06038 |
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Table of Contents:
- Axion dark matter inevitably generates electromagnetic radiation in quantum Hall effect experiments that use strong magnetic fields. Although these emissions are very weak, we have shown using a QCD axion model that they influence the plateau-plateau transition at low temperatures (below $100$ mK) in a system with a large surface area (greater than $10^{-3}\rm cm^2$) of two-dimensional electrons. By analyzing previous experiments that show saturation of the transition width $ΔB$ as temperature and microwave frequency change, we provide evidence for the presence of axions. Notably, in most experiments without axion effects, the saturation frequency $f_s(T)$ is less than $1$ GHz at temperatures of $100$ mK or higher and for system sizes of $10^{-3}\rm cm^2$ or smaller. Additionally, the frequency $f_s(T)$ decreases with decreasing temperature or increasing system size. However, there are experiments that show a saturation frequency $f_s(T)\simeq 2.4$GHz despite a low temperature of 35 mK and a large surface area of $6.6\times 10^{-3}\rm cm^2$ for the Hall bar. This identical frequency of approximately $2.4$ GHz has also been observed in different plateau transitions and in Hall bars of varying sizes. These unexpected results are caused by axion microwaves. The saturation frequency $f_s=m_a/2π$ of $\simeq 2.4$ GHz implies an axion mass of $\simeq 10^{-5}$eV. By comparing the axion effect with thermal effect on the width $ΔB$, we have shown the dominance of the axion effect over thermal effect at low temperature less than $50$mK. The dominance of the axion effect is attributed to significant absorption of axion energy, which is proportional to the square of the number of electrons involved.