Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes.
Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.
Department of Applied Science, College of William and Mary, 251 Jamestown Road, Williamsburg, Virginia 23187, USA.
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Ma
Department of Applied Science, College of William and Mary, 251 Jamestown Road, Williamsburg, Virginia 23187, USA.
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Fang
State Key Laboratory of Surface Physics, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
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Li
State Key Laboratory of Surface Physics, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
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Zhu
State Key Laboratory of Surface Physics, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
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Yang
State Key Laboratory of Surface Physics, Department of Physics, and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433, China.
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Wu
Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, Fudan University, Shanghai, 200433, China.
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Zhao
Department of Applied Science, College of William and Mary, 251 Jamestown Road, Williamsburg, Virginia 23187, USA.
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Lüpke