Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy
In this paper, micromagnetic simulations are employed to investigate terahertz (THz) magnetic excitations in a spin torque nano-oscillator (STNO) with a perpendicularly magnetized synthetic antiferromagnetic (SAF) free layer. The magnetization precession of the free layer can be finely tuned into th...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2024-01-01
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| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/5.0187862 |
| _version_ | 1797331923631079424 |
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| author | Cuixiu Zheng Chao Chen Shanshan Hu Sai Zhou Hao-Hsuan Chen Yaowen Liu |
| author_facet | Cuixiu Zheng Chao Chen Shanshan Hu Sai Zhou Hao-Hsuan Chen Yaowen Liu |
| author_sort | Cuixiu Zheng |
| collection | DOAJ |
| description | In this paper, micromagnetic simulations are employed to investigate terahertz (THz) magnetic excitations in a spin torque nano-oscillator (STNO) with a perpendicularly magnetized synthetic antiferromagnetic (SAF) free layer. The magnetization precession of the free layer can be finely tuned into the sub-THz range without the necessity of external magnetic fields. The excited frequency exhibits two distinctive regions, namely region-I and region-II, depending on the applied current strength. In region-I, characterized by relatively small currents, the two ferromagnetic layers are stabilized at two separate precession orbits. The frequency in this region decreases with current strength, exhibiting similar features as the Néel vector change observed in antiferromagnets. In contrast, region-II is defined by currents where the two ferromagnetic layers synchronize into the same precession orbit. The frequency increases with current, correlating with the variation in the net magnetization of the SAF layer. An analytical model is developed through the canonical transformation of Lagrange’s equation, which can describe the frequency dependence on both the applied current and the antiferromagnetic interlayer coupling strengths. The simulations and the analytical model show good agreement, offering a more profound understanding of the magnetic excitation properties in STNOs with ultrathin SAF free layers. These insights are crucial for the design of advanced terahertz spintronic devices. |
| first_indexed | 2024-03-08T07:42:19Z |
| format | Article |
| id | doaj.art-c79af8d19d3c4f17bd7c819517643097 |
| institution | Directory Open Access Journal |
| issn | 2166-532X |
| language | English |
| last_indexed | 2024-03-08T07:42:19Z |
| publishDate | 2024-01-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | APL Materials |
| spelling | doaj.art-c79af8d19d3c4f17bd7c8195176430972024-02-02T16:57:37ZengAIP Publishing LLCAPL Materials2166-532X2024-01-01121011114011114-710.1063/5.0187862Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropyCuixiu Zheng0Chao Chen1Shanshan Hu2Sai Zhou3Hao-Hsuan Chen4Yaowen Liu5School of Physics Science and Engineering, Tongji University, Shanghai 200092, ChinaSchool of Physics Science and Engineering, Tongji University, Shanghai 200092, ChinaSchool of Physics Science and Engineering, Tongji University, Shanghai 200092, ChinaSchool of Physics Science and Engineering, Tongji University, Shanghai 200092, ChinaShanghai Key Laboratory for Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092, ChinaSchool of Physics Science and Engineering, Tongji University, Shanghai 200092, ChinaIn this paper, micromagnetic simulations are employed to investigate terahertz (THz) magnetic excitations in a spin torque nano-oscillator (STNO) with a perpendicularly magnetized synthetic antiferromagnetic (SAF) free layer. The magnetization precession of the free layer can be finely tuned into the sub-THz range without the necessity of external magnetic fields. The excited frequency exhibits two distinctive regions, namely region-I and region-II, depending on the applied current strength. In region-I, characterized by relatively small currents, the two ferromagnetic layers are stabilized at two separate precession orbits. The frequency in this region decreases with current strength, exhibiting similar features as the Néel vector change observed in antiferromagnets. In contrast, region-II is defined by currents where the two ferromagnetic layers synchronize into the same precession orbit. The frequency increases with current, correlating with the variation in the net magnetization of the SAF layer. An analytical model is developed through the canonical transformation of Lagrange’s equation, which can describe the frequency dependence on both the applied current and the antiferromagnetic interlayer coupling strengths. The simulations and the analytical model show good agreement, offering a more profound understanding of the magnetic excitation properties in STNOs with ultrathin SAF free layers. These insights are crucial for the design of advanced terahertz spintronic devices.http://dx.doi.org/10.1063/5.0187862 |
| spellingShingle | Cuixiu Zheng Chao Chen Shanshan Hu Sai Zhou Hao-Hsuan Chen Yaowen Liu Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy APL Materials |
| title | Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| title_full | Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| title_fullStr | Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| title_full_unstemmed | Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| title_short | Sub-terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| title_sort | sub terahertz excitations in a synthetic antiferromagnet with perpendicular anisotropy |
| url | http://dx.doi.org/10.1063/5.0187862 |
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