Magnetization fluctuations and magnetic aftereffect probed via the anomalous Hall effect
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arXiv
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| Autores principales: | , , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866911785783656448 |
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| author | Nabben, Nadine Sala, Giacomo Nowak, Ulrich Krüger, Matthias Goennenwein, Sebastian T. B. |
| author_facet | Nabben, Nadine Sala, Giacomo Nowak, Ulrich Krüger, Matthias Goennenwein, Sebastian T. B. |
| contents | Taking advantage of the anomalous Hall effect, we electrically probe low-frequency magnetization fluctuations at room temperature in a thin ferromagnetic Pt/Co/AlO$_x$ layer stack with perpendicular magnetic anisotropy. We observe a strong enhancement of the Hall voltage fluctuations within the hysteretic region of the magnetization loop. Analyzing both the temporal evolution of the anomalous Hall voltage and its frequency-dependent noise power density, we identify two types of magnetic noise: abrupt changes in the magnetic domain configuration, evident as Barkhausen-like steps in the Hall voltage time trace, yield a noise power density spectrum scaling with frequency as $1/f^β$ with $β\approx 1.9$. In contrast, quasi-stationary magnetization configurations are connected with a magnetic noise power density with an exponent $β\approx 0.9$. The observation of Barkausen steps and relaxation effects shows that the magnetic system is in a non-stationary state in the hysteresis region, such that the fluctuation-dissipation theorem cannot be expected to hold. However, the time-dependent change in the Hall voltage for constant magnetic field strength resembles the integrated noise power. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_18436 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Magnetization fluctuations and magnetic aftereffect probed via the anomalous Hall effect Nabben, Nadine Sala, Giacomo Nowak, Ulrich Krüger, Matthias Goennenwein, Sebastian T. B. Mesoscale and Nanoscale Physics Taking advantage of the anomalous Hall effect, we electrically probe low-frequency magnetization fluctuations at room temperature in a thin ferromagnetic Pt/Co/AlO$_x$ layer stack with perpendicular magnetic anisotropy. We observe a strong enhancement of the Hall voltage fluctuations within the hysteretic region of the magnetization loop. Analyzing both the temporal evolution of the anomalous Hall voltage and its frequency-dependent noise power density, we identify two types of magnetic noise: abrupt changes in the magnetic domain configuration, evident as Barkhausen-like steps in the Hall voltage time trace, yield a noise power density spectrum scaling with frequency as $1/f^β$ with $β\approx 1.9$. In contrast, quasi-stationary magnetization configurations are connected with a magnetic noise power density with an exponent $β\approx 0.9$. The observation of Barkausen steps and relaxation effects shows that the magnetic system is in a non-stationary state in the hysteresis region, such that the fluctuation-dissipation theorem cannot be expected to hold. However, the time-dependent change in the Hall voltage for constant magnetic field strength resembles the integrated noise power. |
| title | Magnetization fluctuations and magnetic aftereffect probed via the anomalous Hall effect |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2402.18436 |