The variation of magnetic anisotropy with Gd/Co double wedge thickness on Pt(111)
Liang-Wei Lan1,2*, Aldrin Chang1, Wei-Ming Li3, Swati Kanojia1, Jyun-Syong Jhuang4, Wei-Sheng Chiu4, Chii-bin Wu3, Tzu-Hung Chuang4, Chien-Cheng Kuo1
1Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2Internal PhD program of science, National Sun Yat-sen University, Kaohsiung, Taiwan
3Department of Physics, Chung Yuan Christian University, Taoyuan, Taiwan
4National Synchrotron Radiation Center, Hsinchu, Taiwan
* Presenter:Liang-Wei Lan,
Antiferromagnets were originally thought to be an unuseful material but attracted much attention this decade by the high frequency (THz) resonance signal response [1,2,3]. Compared with the GHz signal [4,5] in ferromagnetic materials, antiferromagnetic materials provide a new platform for spintronics and storage devices. However, there is a challenge of zero net magnetic moments which makes antiferromagnetic material hard to control. Synthesis antiferromagnets (SAF) are one of the solutions provided by two ferromagnetic combinations with antiferromagnetic interlayer coupling [6]. Transition metal and Rare earth combination is a promising candidate, especially while two elements reveal rich magnetic behaviors, like Co and Gd. Co-Gd already shows the antiferromagnetic coupling naturally [7] but still lacks the magnetic microstructure information. How the spin configuration evolves and magnetic domain evolution with the thickness of the ultrathin film is a vital issue in spintronics. Magnetic anisotropy plays the dominant role in the interface coupling of Co and Gd ultrathin film.
This study utilizes the double-wedge design with element-sensitive magnetic microscopy to perform a comprehensive and systematic study to address the mentioned issues. The whole experiment is performed by the photoemission electron microscopy with X-ray magnetic circular dichroism (XMCD-PEEM) and magnetic optical Kerr effect (MOKE) in TLS-05B2 at NSRRC. Out-of-plane domains, spin reorientation transition (SRT) region and in-plane domains were observed in 1-4 ML, 4-5 ML, and > 5 ML Co on Pt(111). With the increasing Gd thickness, the SRT region goes from 2 ML to 4 ML. Base on the fitting result of SRT variation, the magnetic anisotropy constant can be systematically conducted.

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Keywords: synthetic antiferromagnets, Gd/Co, photoemission electron microscopy (PEEM), magnetic optical Kerr effect (MOKE)