Abstract
Antiferromagnets (AFMs) have the potential to push spintronic devices from a static condition or gigahertz frequency range to the terahertz range for the sake of high-speed processing. However, the insensitivity of AFMs to magnetic fields makes the manipulation of spin currents difficult. The ultrafast generation of the spin current in ferromagnet/heavy-metal (HM) structures has received a lot of attention in recent years, but whether a similar scenario can be observed in an AFM/HM system is still unknown. Here, we show the optical generation of ultrafast spin current in an AFM/HM heterostructure at zero external magnetic field and at room temperature by detecting the associated terahertz emission. We believe that this is a common phenomenon in antiferromagnets with strong nonlinear optical effects. Our results open an avenue of fundamental research into antiferromagnetism and a route to AFM spintronic devices.
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Acknowledgements
This work was partially supported by the National Natural Science Foundation of China (grant nos. 61521001, 61731010, 61671234, 11727808 and 11674159), National Key Research and Development Program of China (grant nos. 2017YFA0700202 and 2017YFA0303202), and Natural Science Foundation of Jiangsu Province (grant no. BK20190300). It was also partially supported by the Fundamental Research Funds for the Central Universities and by the Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves. We acknowledge B. G. Wang and C. Zhang for their discussion on the mechanism of the spin current generation. We thank Y. F. Nie for helping to confirm the crystallographic orientation of the sample through the φ-scan measurement.
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D.W. and B.J. conceived and instructed this work. L.Z. and Y.T. fabricated and characterized the AFM/NM samples. H.Q. built the terahertz emission setup on the basis of preliminary work by C.Z. and performed the terahertz experiments. S.C. and S.M. provided the high-quality HAADF-STEM image. H.Z. and Q.Z. provided very revealing comments on the physical mechanism of the ultrafast interaction between light and matter. J.W., J.C. and P.W. contributed to the electrodynamic explanations for the THz experiments. H.Q. and L.Z. analysed experimental data and wrote the manuscript with contributions from all of the authors.
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Supplementary information
Supplementary Information
Supplementary Sections 1–5 and Figs. 1–9.
Supplementary Data
The reflective high energy diffraction patterns and X-ray diffraction pattern of samples.
Supplementary Data
The X-ray diffraction φ-scan of samples.
Supplementary Data
The X-ray photoelectron spectroscopy of samples.
Supplementary Data
The polarization state of THz emission from the samples.
Supplementary Data
The dependence of THz waveforms on the sample orientation.
Supplementary Data
The influence of the field-cooling process of samples.
Source data
Source Data Fig. 1
A typical terahertz waveform and its spectrum.
Source Data Fig. 2
Effect of the NM layers and the state of the laser polarization.
Source Data Fig. 3
Impact of the sample azimuth and laser polarization.
Source Data Fig. 4
Effect of the crystallographic orientation of NiO.
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Qiu, H., Zhou, L., Zhang, C. et al. Ultrafast spin current generated from an antiferromagnet. Nat. Phys. 17, 388–394 (2021). https://doi.org/10.1038/s41567-020-01061-7
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DOI: https://doi.org/10.1038/s41567-020-01061-7
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