Zhang Xiaoqian, Xu Huanfeng, Lai Bolin, Lu Qiangsheng, Lu Xianyang, Chen Yequan, Niu Wei, Gu Chenyi, Liu Wenqing, Wang Xuefeng, Liu Chang, Nie Yuefeng, He Liang, Xu Yongbing
Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, China.
Department of Physics, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
Sci Rep. 2018 May 23;8(1):8074. doi: 10.1038/s41598-018-26285-9.
We have studied the CoFeAl thin films with different thicknesses epitaxially grown on GaAs (001) by molecular beam epitaxy. The magnetic properties and spin polarization of the films were investigated by in-situ magneto-optic Kerr effect (MOKE) measurement and spin-resolved angle-resolved photoemission spectroscopy (spin-ARPES) at 300 K, respectively. High spin polarization of 58% (±7%) was observed for the film with thickness of 21 unit cells (uc), for the first time. However, when the thickness decreases to 2.5 uc, the spin polarization falls to 29% (±2%) only. This change is also accompanied by a magnetic transition at 4 uc characterized by the MOKE intensity. Above it, the film's magnetization reaches the bulk value of 1000 emu/cm. Our findings set a lower limit on the thickness of CoFeAl films, which possesses both high spin polarization and large magnetization.
我们通过分子束外延研究了在 GaAs(001)上外延生长的不同厚度的 CoFeAl 薄膜。分别在 300 K 下通过原位磁光克尔效应（MOKE）测量和自旋分辨角分辨光电子能谱（spin-ARPES）研究了薄膜的磁性和自旋极化。首次在厚度为 21 个晶胞（uc）的薄膜中观察到 58%（±7%）的高自旋极化。然而，当厚度减小到 2.5 uc 时，自旋极化仅降至 29%（±2%）。这种变化还伴随着在 4 uc 处由 MOKE 强度表征的磁性转变。在此之上，薄膜的磁化强度达到 1000 emu/cm 的体值。我们的研究结果设定了同时具有高自旋极化和大磁化强度的 CoFeAl 薄膜厚度的下限。
