| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Tuning Surface Spin Polarization of CoFeB by Boron Diffusion Detected by Spin Resolved Photoemission |
| Qi Liu1†, Xianyang Lu1,4†*, Chengrui Fu2, Jiarui Chen3, Zhe Zhang1, Yuting Gong1, Xinyue Wang1, Yu Yan1,4, Qinwu Gao1, Hui Li2*, Xuezhong Ruan1, Yao Li1, Jun Du3, Jing Wu4, Liang He1, Bo Liu5, Rong Zhang1, and Yongbing Xu1,4* |
1Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
2Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan 250061, China
3Department of Physics, Nanjing University, Nanjing 210093, China
4York-Nanjing Joint Center (YNJC) for Spintronics and Nano-engineering, Department of Electronics and Physics, University of York, York YO10 5DD, UK
5Key Laboratory of Spintronics Materials, Devices and Systems of Zhejiang Province, Hangzhou 311300, China
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| Cite this article: |
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Qi Liu, Xianyang Lu, Chengrui Fu et al 2023 Chin. Phys. Lett. 40 087302 |
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Abstract Research of spin polarization of magnetic CoFeB thin films is of practical importance in spintronic applications. Here, using a direct characterization technique of spin-resolved photoemission spectroscopy, we obtain the surface spin polarization of amorphous Co$_{40}$Fe$_{40}$B$_{20}$ thin films with different annealing temperatures from 100 ℃ to 500 ℃ prepared by magnetron sputtering. After high annealing temperature, a quasi-semiconductor state is gradually formed at the CoFeB surface due to the boron diffusion. While the global magnetization remains almost constant, the secondary electrons' spin polarization, average valence band spin polarization and the spin polarization at Fermi level from spin-resolved photoemission spectroscopy show a general trend of decreasing with the increasing annealing temperature above 100 ℃. These distinct surface properties are attributed to the enhanced Fe–B bonding due to the boron segregation upon surface after annealing as confirmed by x-ray photoelectron spectroscopy and scanning transmission electron microscopy with energy dispersive spectroscopy. Our findings provide insight into the surface spin-resolved electronic structure of the CoFeB thin films, which should be important for development of high-performance magnetic random-access memories.
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Received: 06 May 2023
Published: 09 August 2023
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| PACS: |
61.43.Dq
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(Amorphous semiconductors, metals, and alloys)
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73.20.-r
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(Electron states at surfaces and interfaces)
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29.30.-h
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(Spectrometers and spectroscopic techniques)
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| [1] | Julliere M 1975 Phys. Lett. A 54 225 |
| [2] | Meng H, Sbiaa R, Lua S Y H, Wang C C, Akhtar M A K, Wong S K, Luo P, Carlberg C J P, and Ang K S A 2011 J. Phys. D 44 405001 |
| [3] | Zhang W, Wong P K J, Zhou X C, Rath A, Huang Z C, Wang H Y, Morton S A, Yuan J R, Zhang L, Chua R, Zeng S W, Liu E, Feng X, Ariando, Chua D H C, Feng Y P, van der Laan G, Pennycook S J, Zhai Y, and Wee A T S 2019 ACS Nano 13 2253 |
| [4] | Wang D, Nordman C, Daughton J M, Qian Z, Fink J, Wang D, Nordman C, Daughton J M, Qian Z, and Fink J 2004 IEEE Trans. Magn. 40 2269 |
| [5] | Djayaprawira D D, Tsunekawa K, Nagai M, Maehara H, Yamagata S, Watanabe N, Yuasa S, Suzuki Y, and Ando K 2005 Appl. Phys. Lett. 86 092502 |
| [6] | Ikeda S, Hayakawa J, Ashizawa Y, Lee Y M, Miura K, Hasegawa H, Tsunoda M, Matsukura F, and Ohno H 2008 Appl. Phys. Lett. 93 082508 |
| [7] | MacLaren J M, Zhang X G, and Butler W H 1997 Phys. Rev. B 56 11827 |
| [8] | Diao Z T, Apalkov D, Pakala M, Ding Y F, Panchula A, and Huai Y M 2005 Appl. Phys. Lett. 87 232502 |
| [9] | Zhang X Y, Vernier N, Vila L, Yan S H, Cao Z Q, Cao A N, Wang Z L, Cai W L, Liu Y, Yang H W, Ravelosona D, and Zhao W S 2019 Phys. Rev. Appl. 11 054041 |
| [10] | Huang S X, Chen T Y, and Chien C L 2008 Appl. Phys. Lett. 92 242509 |
| [11] | Paluskar P V, Kohlhepp J T, Swagten H J M, and Koopmans B 2006 J. Appl. Phys. 99 08e503 |
| [12] | Paluskar P V, Kohlhepp J T, Swagten H J M, Koopmans B, Wolters R, Boeve H, and Snoeck E 2007 J. Phys. D 40 1234 |
| [13] | Swagten H J M, Paluskar P V, Lavrijsen R, Kohlhepp J T, and Koopmans B 2007 J. Magn. Magn. Mater. 310 2012 |
| [14] | Paluskar P V, Lavrijsen R, Sicot M, Kohlhepp J T, Swagten H J, and Koopmans B 2009 Phys. Rev. Lett. 102 016602 |
| [15] | Li Z P, li S P, Zheng Y K, Fang J S, Chen L F, Hong L, and Wang H F 2016 Appl. Phys. Lett. 109 182403 |
| [16] | Lou Y L, Zhang Y M, Guo H, Xu D Q, and Zhang Y M 2017 J. Semicond. 38 062003 |
| [17] | Zhang X Q, Xu H F, Lai B L, Lu Q S, Lu X Y, Chen Y Q, Niu W, Gu C Y, Liu W Q, Wang X F, Liu C, Nie Y F, He L, and Xu Y B 2018 Sci. Rep. 8 8074 |
| [18] | Cardoso S, Cavaco C, Ferreira R, Pereira L, Rickart M, Freitas P P, Franco N, Gouveia J, and Barradas N P 2005 J. Appl. Phys. 97 10C916 |
| [19] | Hopster H, Kurzawa R, Raue R, Schmitt W, Guntherodt G, Walker K H, and Guntherodt H J 1985 J. Phys. F 15 L11 |
| [20] | Seah M P and Dench W A 1979 Surf. Interface Anal. 1 2 |
| [21] | Zhang Z, Lu X, Yan Y, Lu J, Li Z, Liu Q, Zhu F, Cao J, Wang Y, Huang Z, Zhai Y, Li Y, Ruan X, He L, Wu J, Du J, Zhang R, and Xu Y 2022 Appl. Phys. Lett. 120 182403 |
| [22] | Seddon E A 2016 Spin-Resolved Valence Photoemission. In Xu Y, Awschalom D, and Nitta J (eds) Handbook of Spintronics (Berlin: Spinger) pp 831–918 |
| [23] | Xu Y B, Greig D, Seddon E A, Cornelius S, and Matthew J A D 1999 IEEE Trans. Magn. 35 3427 |
| [24] | Xu Y B, Greig D, Seddon E A, and Matthew J A D 2000 J. Appl. Phys. 87 7136 |
| [25] | Hopster H 1987 Phys. Rev. B 36 2325 |
| [26] | Kresse G and Furthmuller J 1996 Phys. Rev. B 54 11169 |
| [27] | Kresse G and Hafner J 1993 Phys. Rev. B 47 558 |
| [28] | Yeh J J and Lindau I 1985 At. Data Nucl. Data Tables 32 1 |
| [29] | Xu Y B, Greig D, Seddon E A, and Matthew J A D 1997 Phys. Rev. B 55 11442 |
| [30] | Stöhr J and Siegmann H C 2006 Springer Series in Solid-State Sciences (Berlin: Springer) vol 152 p 216 |
| [31] | Penn D R, Apell S P, and Girvin S M 1985 Phys. Rev. Lett. 55 518 |
| [32] | Tanaka H, Takayama S, Hasegawa M, Fukunaga T, Mizutani U, Fujita A, and Fukamichi K 1993 Phys. Rev. B 47 2671 |
| [33] | Hafner J, Tegze M, and Becker C 1994 Phys. Rev. B 49 285 |
| [34] | Schmitt W, Hopster H, and Guntherodt G 1985 Phys. Rev. B 31 4035 |
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