Probing the fluctuating magnetic field of Fe-triazole spin-crossover thin-layers with nitrogen-vacancy centers in diamond
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arXiv
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| Auteurs principaux: | , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866908321455276032 |
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| author | Barbosa, Isabel Cardoso Hochdörffer, Tim Wolny, Juliusz A. Lönard, Dennis Johansson, Stefan Gutsche, Jonas Schünemann, Volker Widera, Artur |
| author_facet | Barbosa, Isabel Cardoso Hochdörffer, Tim Wolny, Juliusz A. Lönard, Dennis Johansson, Stefan Gutsche, Jonas Schünemann, Volker Widera, Artur |
| contents | Fe$^{\mathrm{II}}$ spin-crossover (SCO) complexes are materials that change their magnetic properties upon temperature variation, exhibiting a thermal hysteresis. Particularly interesting for magnetic-memory applications are thin layers of SCO complexes, where practical magnetic probing techniques are required. While conventional magnetometry on SCO complexes employs cryogenic temperatures, nitrogen-vacancy (NV) centers are quantum magnetometers that can operate at room temperature with high spatial resolution and magnetic-field sensitivity. In this work, we apply thin layers of Fe-triazole SCO complexes directly onto a single-crystal diamond with shallow NV centers working as magnetic sensors and probe the fluctuating magnetic field. Using temperature-dependent NV-center $T_1$ measurements and a widefield technique, we find that the complexes are paramagnetic in the investigated temperature range from 20 °C to 80 °C. We quantitatively describe the $T_1$ time by a model considering the fluctuating magnetic field of the Fe$^{\mathrm{II}}$ ions. We see signatures of a local change of spin state in the $T_1$ relaxometry data, but structural changes in the SCO material dominate the local magnetic environment of the NV centers. Moreover, we conduct a Hahn echo to measure the $T_2$ time, which contrasts the findings of the $T_1$ times for the SCO complexes. We attribute this to different NV detection sensitivities towards Fe$^{\mathrm{II}}$ and Fe$^{\mathrm{III}}$ of the protocols. Our results on the magnetic properties of SCO materials highlight the capabilities of the NV center as a susceptible sensor for fluctuating magnetic fields. At the same time, a spin switching of the complexes cannot be observed due to the systematic challenges when working on nanometer distances to the SCO thin layers. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_14454 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Probing the fluctuating magnetic field of Fe-triazole spin-crossover thin-layers with nitrogen-vacancy centers in diamond Barbosa, Isabel Cardoso Hochdörffer, Tim Wolny, Juliusz A. Lönard, Dennis Johansson, Stefan Gutsche, Jonas Schünemann, Volker Widera, Artur Materials Science Quantum Physics Fe$^{\mathrm{II}}$ spin-crossover (SCO) complexes are materials that change their magnetic properties upon temperature variation, exhibiting a thermal hysteresis. Particularly interesting for magnetic-memory applications are thin layers of SCO complexes, where practical magnetic probing techniques are required. While conventional magnetometry on SCO complexes employs cryogenic temperatures, nitrogen-vacancy (NV) centers are quantum magnetometers that can operate at room temperature with high spatial resolution and magnetic-field sensitivity. In this work, we apply thin layers of Fe-triazole SCO complexes directly onto a single-crystal diamond with shallow NV centers working as magnetic sensors and probe the fluctuating magnetic field. Using temperature-dependent NV-center $T_1$ measurements and a widefield technique, we find that the complexes are paramagnetic in the investigated temperature range from 20 °C to 80 °C. We quantitatively describe the $T_1$ time by a model considering the fluctuating magnetic field of the Fe$^{\mathrm{II}}$ ions. We see signatures of a local change of spin state in the $T_1$ relaxometry data, but structural changes in the SCO material dominate the local magnetic environment of the NV centers. Moreover, we conduct a Hahn echo to measure the $T_2$ time, which contrasts the findings of the $T_1$ times for the SCO complexes. We attribute this to different NV detection sensitivities towards Fe$^{\mathrm{II}}$ and Fe$^{\mathrm{III}}$ of the protocols. Our results on the magnetic properties of SCO materials highlight the capabilities of the NV center as a susceptible sensor for fluctuating magnetic fields. At the same time, a spin switching of the complexes cannot be observed due to the systematic challenges when working on nanometer distances to the SCO thin layers. |
| title | Probing the fluctuating magnetic field of Fe-triazole spin-crossover thin-layers with nitrogen-vacancy centers in diamond |
| topic | Materials Science Quantum Physics |
| url | https://arxiv.org/abs/2411.14454 |