All-optical magnetometric characterization of the antiferromagnetic exchange-spring system Mn$_2$Au|Py by terahertz spin-torques
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866917787687976960 |
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| author | Behovits, Yannic Chekhov, Alexander L. Serrano, Bruno Rosinus Ruge, Amon Reimers, Sonka Lytvynenko, Yaryna Kläui, Mathias Jourdan, Martin Kampfrath, Tobias |
| author_facet | Behovits, Yannic Chekhov, Alexander L. Serrano, Bruno Rosinus Ruge, Amon Reimers, Sonka Lytvynenko, Yaryna Kläui, Mathias Jourdan, Martin Kampfrath, Tobias |
| contents | Antiferromagnetic materials have great potential for spintronic applications at terahertz (THz) frequencies. However, in contrast to ferromagnets, experimental studies of antiferromagnets are often challenging due to a lack of straightforward external control of the Néel vector $\mathbf{L}$. Here, we study an AFM|FM stack consisting of an antiferromagnetic metal layer (AFM) of the novel material Mn2Au and a ferromagnetic metal layer (FM) of NiFe. In this exchange-spring system, $\mathbf{L}$ of AFM Mn2Au can be controlled by the application of an external magnetic field B_ext. To characterize the AFM|FM stack as a function of the quasi-static $\mathbf{B}_{\mathrm{ext}}$, we perform THz-pump magneto-optic probe experiments. We identify signal components that can consistently be explained by the in-plane antiferromagnetic magnon mode excited by field-like Néel spin-orbit torques (NSOTs). Remarkably, we find that the $\mathbf{B}_{\mathrm{ext}}$- and THz-pump-induced changes in the optical response of the sample are dominated exclusively by the spin degrees of freedom of AFM. We fully calibrate the magnetic circular and magnetic linear optical birefringence of AFM and extract the efficiency of the NSOTs. Finally, by selective excitation of domains with different orientation of $\mathbf{L}$, we are able to determine the relative volume fraction of 0°, 90°, 180° and 270° domains distribution during the quasi-static reversal of $\mathbf{L}$ by $\mathbf{B}_{\mathrm{ext}}$. Our insights are an important prerequisite for future studies of ultrafast coherent switching of spins by THz NSOTs and show that THz-pump magneto-optic-probe experiments are a powerful tool to characterize magnetic properties of antiferromagnets. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2409_18107 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | All-optical magnetometric characterization of the antiferromagnetic exchange-spring system Mn$_2$Au|Py by terahertz spin-torques Behovits, Yannic Chekhov, Alexander L. Serrano, Bruno Rosinus Ruge, Amon Reimers, Sonka Lytvynenko, Yaryna Kläui, Mathias Jourdan, Martin Kampfrath, Tobias Mesoscale and Nanoscale Physics Antiferromagnetic materials have great potential for spintronic applications at terahertz (THz) frequencies. However, in contrast to ferromagnets, experimental studies of antiferromagnets are often challenging due to a lack of straightforward external control of the Néel vector $\mathbf{L}$. Here, we study an AFM|FM stack consisting of an antiferromagnetic metal layer (AFM) of the novel material Mn2Au and a ferromagnetic metal layer (FM) of NiFe. In this exchange-spring system, $\mathbf{L}$ of AFM Mn2Au can be controlled by the application of an external magnetic field B_ext. To characterize the AFM|FM stack as a function of the quasi-static $\mathbf{B}_{\mathrm{ext}}$, we perform THz-pump magneto-optic probe experiments. We identify signal components that can consistently be explained by the in-plane antiferromagnetic magnon mode excited by field-like Néel spin-orbit torques (NSOTs). Remarkably, we find that the $\mathbf{B}_{\mathrm{ext}}$- and THz-pump-induced changes in the optical response of the sample are dominated exclusively by the spin degrees of freedom of AFM. We fully calibrate the magnetic circular and magnetic linear optical birefringence of AFM and extract the efficiency of the NSOTs. Finally, by selective excitation of domains with different orientation of $\mathbf{L}$, we are able to determine the relative volume fraction of 0°, 90°, 180° and 270° domains distribution during the quasi-static reversal of $\mathbf{L}$ by $\mathbf{B}_{\mathrm{ext}}$. Our insights are an important prerequisite for future studies of ultrafast coherent switching of spins by THz NSOTs and show that THz-pump magneto-optic-probe experiments are a powerful tool to characterize magnetic properties of antiferromagnets. |
| title | All-optical magnetometric characterization of the antiferromagnetic exchange-spring system Mn$_2$Au|Py by terahertz spin-torques |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2409.18107 |