Kong Chongtao, Song Lin, Zhao Xupeng, Wang Hailong, Zhao Jianhua, Yuan Guodong, Zhang Xinhui
State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Appl Mater Interfaces. 2024 Apr 3;16(13):17041-17050. doi: 10.1021/acsami.4c01858. Epub 2024 Mar 22.
The ultrafast manipulation of spin in ferromagnet-semiconductor (FM/SC) heterojunctions is a key issue for advancing spintronics, where magnetic damping and interfacial spin transport often define device efficiency. Leveraging selective optical excitation in semiconductors offers a unique approach to spin manipulation in FM/SC heterojunctions. Herein, we investigated the magnetic dynamics of a CoFeAl/-GaAs heterojunction using the time-resolved magneto-optical Kerr technique and observed the considerably enhanced magnetic damping of CoFeAl when GaAs is photoexcited near its band edge. This enhancement is attributed to an enhanced spin-pumping effect facilitated by spin-dependent carrier tunneling and capture within the CoFeAl layer. Moreover, circularly polarized light excites spin-polarized band-edge photocarriers, further impacting the magnetic damping of CoFeAl through an additional optical spin-transfer torque on the magnetic moment of CoFeAl. Our results provide a valuable reference for manipulating spin-pumping and interfacial spin transport in FM/SC heterojunctions, showcasing the advantage of optical control of semiconductor photocarriers for the ultrafast manipulation of magnetic dynamics and interfacial spin transfer.
铁磁体-半导体（FM/SC）异质结中自旋的超快操纵是推动自旋电子学发展的关键问题，其中磁阻尼和界面自旋输运常常决定了器件效率。利用半导体中的选择性光激发为FM/SC异质结中的自旋操纵提供了一种独特方法。在此，我们使用时间分辨磁光克尔技术研究了CoFeAl/-GaAs异质结的磁动力学，并观察到当GaAs在其带边附近被光激发时，CoFeAl的磁阻尼显著增强。这种增强归因于自旋相关的载流子隧穿和在CoFeAl层内的俘获所促进的自旋泵浦效应增强。此外，圆偏振光激发自旋极化的带边光载流子，通过对CoFeAl磁矩的额外光学自旋转移力矩进一步影响CoFeAl的磁阻尼。我们的结果为操纵FM/SC异质结中的自旋泵浦和界面自旋输运提供了有价值的参考，展示了利用半导体光载流子的光学控制实现磁动力学和界面自旋转移超快操纵的优势。
