日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 82, No. 05 (2018),
pp. 140-146

Correlation between the Effective Amounts of Elements in TbFeCo Thin Films and Their Magnetic Properties

Ryosuke Hara 1, Haruki Yamane 2, Yasuyoshi Isaji 3, Masanobu Kobayashi 4, Akimitsu Morisako 5, Xiaoxi Liu 5 and Yukiko Yasukawa 6

1 Graduate School of Engineering, Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology
2 Division of Electronic Light Application and Development, Akita Industrial Technology Center
3 Graduate School of Engineering, Chiba Institute of Technology
4 Department of Advanced Materials Science and Engineering, Faculty of Engineering, Chiba Institute of Technology
5 Department of Electrical and Computer Engineering, Faculty of Engineering, Shinshu University
6 Department of Electrical and Electronic Engineering, Faculty of Engineering, Chiba Institute of Technology

Abstract:

In this study, TbFeCo thin films were prepared using DC-magnetron sputtering technique utilizing a conventional batch-type sputtering machine. The magnetic properties such as magnetic hysteresis loops and magneto-optical properties of the obtained films were measured. Furthermore, we precisely evaluated the “effective” amounts of elements, i.e., the amounts of constituents released by oxidation, in TbFeCo thin films. We also attempted to control the amounts of effective elements by changing the pre-sputtering condition before film preparation. This is because the pre-sputtering process greatly affected the effective amounts of elements in the prepared TbFeCo thin films, such that the magnetic properties were drastically different from sample to sample by altering the pre-sputtering condition. Insufficient pre-sputtering led to a relatively high oxygen content in the films in comparison with those prepared with sufficient pre-sputtering. Outstanding perpendicular magnetic anisotropy in the out-of-plane direction was observed in a film prepared after 60 min of pre-sputtering, which exhibited a coercivity (Hc) value of 6.4 kOe from magnetic hysteresis measurements and 8.2 kOe from magneto-optical polar Kerr hysteresis measurements at an incident light of wavelength 700 nm. The saturation value of the polar Kerr rotation angle (θK) of this film was approximately 0.3°, which is comparable to the theoretically optimized value. Therefore, we demonstrated that high-quality TbFeCo films can be obtained with high reproducibility by using a simple batch-type sputtering machine and that there is a strong correlation between effective amounts of elements in TbFeCo thin films and their magnetic properties.

[doi:10.2320/jinstmet.J2017041]


(Received 2017/09/14)

Keywords:

terbium iron cobalt magnetic thin film, magnetic property, magneto-optical polar Kerr effect, effective amounts of elements, oxidation


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