| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Terahertz Emission of Ferromagnetic Ni-Fe Thin Films Excited by Ultrafast Laser Pulses |
| SHEN Jian**, ZHANG Huai-Wu, LI Yuan-Xun |
| State Key Laboratory of Electronic Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 |
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| Cite this article: |
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SHEN Jian, ZHANG Huai-Wu, LI Yuan-Xun 2012 Chin. Phys. Lett. 29 067502 |
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Abstract It is believed that the ultrafast demagnetization process in ferromagnetic film is intrinsically a thermal effect, which is induced by ultrafast laser pulses. We present experimental evidence that such ultrafast demagnetization of the NiFe thin film can radiate electromagnetic waves in the terahertz range. We also demonstrate that the magnitude of the terahertz electromagnetic pulse emitted from ferromagnetic films after pulsed laser excitation can be tuned by the Gilbert damping factor α, which is conventionally used to describe damping of GHz precession motion of magnetization. Different damping factors are obtained by varying the normal metal film adjacent to the magnetic film via spin pumping. The measured radiated electric field in the far field is found to be proportional to the Gilbert damping factor.
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Received: 13 March 2012
Published: 31 May 2012
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| PACS: |
75.78.Jp
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(Ultrafast magnetization dynamics and switching)
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42.65.Re
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(Ultrafast processes; optical pulse generation and pulse compression)
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78.47.J-
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(Ultrafast spectroscopy (<1 psec))
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