Separating terahertz spin and charge contributions from ultrathin antiferromagnetic heterostructures
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arXiv
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| Format: | Preprint |
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2024
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| author | Metzger, Thomas W. J. Fischer, Peter Kikkawa, Takashi Saitoh, Eiji Kimel, Alexey V. Bossini, Davide |
| author_facet | Metzger, Thomas W. J. Fischer, Peter Kikkawa, Takashi Saitoh, Eiji Kimel, Alexey V. Bossini, Davide |
| contents | Femtosecond laser excitation of nanometer thin heterostructures comprising a heavy metal and a magnetically ordered material is known to result in the emission of terahertz radiation. However, the nature of the emitted radiation from heavy metal~/~antiferromagnet heterostructures has sparked debates and controversies in the literature. Here, we unambiguously separate spin and charge contributions from Pt~/~NiO heterostructures by introducing an unprecedented methodology combining high external magnetic fields with a symmetry analysis of the emitted terahertz polarization. We observe two distinct mechanisms of terahertz emission which we identify as optical difference frequency generation and ultrafast laser-induced quenching of the magnetization. We emphasize the absence of spin transport effects and signatures of coherent magnons. Overall, our work provides a general experimental methodology to separate spin and charge contributions to the laser-induced terahertz emission from heterostructures comprising a magnetically ordered material thus holding great potential for advancing terahertz spintronics and establishing terahertz orbitronics. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_13870 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Separating terahertz spin and charge contributions from ultrathin antiferromagnetic heterostructures Metzger, Thomas W. J. Fischer, Peter Kikkawa, Takashi Saitoh, Eiji Kimel, Alexey V. Bossini, Davide Mesoscale and Nanoscale Physics Femtosecond laser excitation of nanometer thin heterostructures comprising a heavy metal and a magnetically ordered material is known to result in the emission of terahertz radiation. However, the nature of the emitted radiation from heavy metal~/~antiferromagnet heterostructures has sparked debates and controversies in the literature. Here, we unambiguously separate spin and charge contributions from Pt~/~NiO heterostructures by introducing an unprecedented methodology combining high external magnetic fields with a symmetry analysis of the emitted terahertz polarization. We observe two distinct mechanisms of terahertz emission which we identify as optical difference frequency generation and ultrafast laser-induced quenching of the magnetization. We emphasize the absence of spin transport effects and signatures of coherent magnons. Overall, our work provides a general experimental methodology to separate spin and charge contributions to the laser-induced terahertz emission from heterostructures comprising a magnetically ordered material thus holding great potential for advancing terahertz spintronics and establishing terahertz orbitronics. |
| title | Separating terahertz spin and charge contributions from ultrathin antiferromagnetic heterostructures |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2412.13870 |