Element specific spin and orbital moments of nanoscale CoFeB amorphous thin films on GaAs(100)

Yu Yan,Biao You,Lei Ye,Vlado K Lazarov,Wenqing Liu,Rong Zhang,Hongqing Tu,Jing Wu,Balati Kuerbanjiang,Junlin Wang,Johnny Wong,Xianyang Lu,Cong Lu,Yongbing Xu,Jun Du,Iain Will

doi:10.1063/1.4962994

Yu Yan, Biao You + Show 14 more

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https://doi.org/10.1063/1.4962994

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Abstract

CoFeB amorphous films have been synthesized on GaAs(100) and studied with X-ray magnetic circular dichroism (XMCD) and transmission electron microscopy (TEM). We have found that the ratios of the orbital to spin magnetic moments of both the Co and Fe in the ultrathin amorphous film have been enhanced by more than 300% compared with those of the bulk crystalline Co and Fe, and specifically a large orbital moment of 0.56 μB from the Co atoms has been observed and at the same time the spin moment of the Co atoms remains comparable to that of the bulk hcp Co. The results indicate that the large uniaxial magnetic anisotropy (UMA) observed in the ultrathin CoFeB film on GaAs(100) is related to the enhanced spin-orbital coupling of the Co atoms in the CoFeB. This work offers experimental evidences of the correlation between the UMA and the element specific spin and orbital moments in the CoFeB amorphous film on the GaAs(100) substrate, which is of significance for spintronics applications.

Highlights

Element specific spin and orbital moments of nanoscale CoFeB amorphous thin films on GaAs(100)
To exclude the contribution from magnetocrystalline anisotropy (MCA), and focus on the uniaxial magnetic anisotropy (UMA) in the FM/SC film system, an effective method would to be to alloy the ferromagnetic film with metalloid material in order to create an amorphous magnetic thin films
Several models have been proposed including, bond-orientational anisotropy (BOA),[6,20] Neel-Taniguchi directional pair-ordering model and random anisotropy model,[21] in order to explain the origin of the UMA in CoFeB/GaAs

Summary

Introduction

Element specific spin and orbital moments of nanoscale CoFeB amorphous thin films on GaAs(100) Lazarov,[4] Jing Wu,[1,4] Johnny Wong,[1] Biao You,[3] Jun Du,3,a Rong Zhang[1] and Yongbing Xu1,2,b 1York-Nanjing International Center of Spintronics (YNICS), Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Material, Jiangsu Procincial Key Laboratory for Nanotechnology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China 2Spintronics and Nanodevice laboratory, Department of Electronics, University of York, YO10 5DD, United Kingdom 3National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China 4Department of Physics, University of York, YO10 5DD, United Kingdom 5College of Communication Engineering, Chongqing University, Chongqing 400044, China (Received 14 June 2016; accepted 6 September 2016; published online 13 September 2016)

Results

Conclusion