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金属学报  2018, Vol. 54 Issue (9): 1281-1288    DOI: 10.11900/0412.1961.2017.00492
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倾斜溅射对CoFeB薄膜条纹磁畴结构与磁各向异性的影响
马晓琴1,2, 詹清峰2,3(), 李金财2, 刘青芳1, 王保敏2, 李润伟2
1 兰州大学物理科学与技术学院磁学与磁性材料教育部重点实验室 兰州 730000
2 中国科学院宁波材料技术与工程研究所浙江省磁性材料及其应用技术重点实验室 中国科学院磁性材料与器件重点实验室 宁波 315201
3 华东师范大学物理与材料科学学院精密光谱科学与技术国家重点实验室 上海 200241
Influence of Oblique Sputtering on Stripe Magnetic Domain Structure and Magnetic Anisotropy of CoFeB Thin Films
Xiaoqin MA1,2, Qingfeng ZHAN2,3(), Jincai LI2, Qingfang LIU1, Baomin WANG2, Runwei LI2
1 Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, School of Physical Sciences and Technology, Lanzhou University, Lanzhou 730000, China
2 Key Laboratory of Magnetic Materials and Devices, Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
3 State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China
引用本文:

马晓琴, 詹清峰, 李金财, 刘青芳, 王保敏, 李润伟. 倾斜溅射对CoFeB薄膜条纹磁畴结构与磁各向异性的影响[J]. 金属学报, 2018, 54(9): 1281-1288.
Xiaoqin MA, Qingfeng ZHAN, Jincai LI, Qingfang LIU, Baomin WANG, Runwei LI. Influence of Oblique Sputtering on Stripe Magnetic Domain Structure and Magnetic Anisotropy of CoFeB Thin Films[J]. Acta Metall Sin, 2018, 54(9): 1281-1288.

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摘要: 

利用倾斜溅射的方法制备了非晶CoFeB磁性薄膜,研究了倾斜溅射对非晶CoFeB磁性薄膜条纹磁畴结构、面内静态磁各向异性、面内转动磁各向异性、垂直磁各向异性的影响规律。结果表明,倾斜溅射可以有效地降低CoFeB非晶薄膜条纹磁畴结构出现的临界厚度,无倾斜溅射时,CoFeB薄膜出现条纹磁畴结构的临界厚度大于240 nm,倾斜溅射时,出现条纹磁畴结构的临界厚度小于240 nm。磁性测试结果表明,对于具有条纹磁畴结构的CoFeB薄膜,倾斜溅射不仅可以提高磁性薄膜的面内静态磁各向异性的强度,同时还可以增强面内转动磁各向异性与垂直磁各向异性的强度。随着倾斜溅射角度的逐渐增大,磁各向异性的强度均呈现增大的趋势。XRD和TEM观测结果证明,CoFeB薄膜趋于非晶结构,同时,SEM观察结果表明,CoFeB薄膜虽然不存在长程有序的晶体结构,但依然可以形成柱状结构,由于倾斜溅射技术,形成的柱状结构呈倾斜状态,从而增强了薄膜的垂直磁各向异性,导致条纹磁畴结构的出现。

关键词 CoFeB薄膜条纹磁畴铁磁共振倾斜溅射转动磁各向异性    
Abstract

Magnetic anisotropy is one of the most important fundamental properties of magnetic thin film. The strength of magnetic anisotropy determines the ferromagnetic resonance frequency of magnetic films in the high-frequency applications. Because of the directionality of conventional static magnetic anisotropy in magnetic film, the high-frequency device usually shows an obvious directionality. When the microwave magnetic ?eld deviates from the perpendicular direction of magnetic anisotropy, the devices cannot reveal their best performance. The magnetic ?lm with a stripe magnetic domain structure displays an in-plane rotatable magnetic anisotropy, which can be an important strategy to solve the problem of magnetic ?eld orientation dependent performance in high-frequency device. Therefore, the magnetic domain, the magnetic anisotropy, and the high-frequency behaviors for magnetic ?lms with a stripe magnetic domain structure have received extensive attention. Previously, most of the studies focused on the stripe magnetic domain structure of polycrystalline thin films. However, less attention was paid on amorphous magnetic thin films. Since the amorphous magnetic films have no long-range ordered crystal structure, no magnetocrystalline anisotropy, no grain boundary defects resistance hindering the domain wall displacement, they usually show excellent soft magnetic properties and have been widely applied in high-frequency devices. CoFeB alloy is one of the most important amorphous magnetic materials and has been extensively applied in various spintronic devices. In this work, amorphous CoFeB magnetic thin films were prepared by using a method of oblique sputtering technique at room temperature. The influences of oblique sputtering on the stripe magnetic domain structure, the in-plane static magnetic anisotropy, the in-plane rotational magnetic anisotropy, and the perpendicular magnetic anisotropy of the amorphous CoFeB films were studied by scanning probe microscope, vibrating sample magnetometer, ferromagnetic resonance. It is found that the method of oblique sputtering could effectively reduce the critical thickness for the appearance of stripe magnetic domain in amorphous CoFeB films. For a non-oblique sputtered CoFeB film, the critical thickness for the appearance of the stripe magnetic domain is above 240 nm. In contrast, after been subjected to the oblique sputtering, the critical thickness becomes below 240 nm. The different magnetic characterizations indicate that for the growth of CoFeB films with stripe magnetic domain structure, the oblique sputtering could not only enhance the strength of in-plane static magnetic anisotropy, but also improve the in-plane rotational magnetic anisotropy and the perpendicular magnetic anisotropy. All of the magnetic anisotropies are increased with the angle of oblique sputtering. The observation results of XRD and TEM prove that the prepared CoFeB thin films tend to amorphous structure. The characterization of SEM observation indicates that although the amorphous CoFeB films do not possess long-range ordered crystalline structure, they still could form a kind of columnar structure. The slanted columnar structure of CoFeB films could significantly increase the perpendicular magnetic anisotropy, thus lead to the appearance of stripe magnetic domain structure.

Key wordsCoFeB thin film    stripe magnetic domain    ferromagnetic resonance    oblique sputtering    rotational magnetic anisotropy
收稿日期: 2017-11-27     
ZTFLH:  O469  
基金资助:国家自然科学基金项目 Nos.11674336、51522105、51525103和11627801,国家重点研发计划项目No.2016YFA0201102和宁波市科技创新团队项目No.2015B11001
作者简介: 作者简介 马晓琴,女,1990年生,硕士生
图1  利用倾斜溅射制备CoFeB磁性薄膜的示意图
图2  不同倾斜溅射角度(β)下制备的CoFeB薄膜的XRD谱
图3  无倾斜溅射(β=0°)的CoFeB薄膜截面的TEM像和SAED花样
图4  不同倾斜溅射角度下生长的CoFeB薄膜的磁滞回线及相应的磁畴图
图5  不同倾斜溅射角度下生长的CoFeB薄膜的磁滞回线剩磁比(Mr/Ms)随磁场与面内静态磁各向异性方向的夹角(θ)的变化关系
图6  不同磁场方向下的铁磁共振测量示意图
图7  不同倾斜溅射角度下生长的CoFeB薄膜的铁磁共振场强度随磁场与θ的变化关系
图8  不同倾斜溅射角度下制备的CoFeB薄膜的铁磁共振场强度随磁场与膜面法线方向间的夹角(θH)的变化关系及倾斜溅射角度为60°时CoFeB薄膜的断面形貌像
图9  倾斜溅射角为45°时生长的不同厚度的CoFeB薄膜的条纹磁畴结构
[1] Phuoc N N, Ong C K.Anomalous temperature dependence of magnetic anisotropy in gradient-composition sputterred thin films[J]. Adv. Mater., 2013, 25: 980
[2] Wei J W, Wang J B, Liu Q F, et al.An induction method to calculate the complex permeability of soft magnetic films without a reference sample[J]. Rev. Sci. Instrum., 2014, 85: 054705
[3] Phuoc N N, Ong C K.Tailoring thermal stability behaviour of magnetic thin films by hybrid oblique gradient-composition sputtering[J]. J. Phys., 2013, 46D: 485002
[4] Kittel C.Interpretation of anomalous larmor frequencies in ferromagnetic resonance experiment[J]. Phys. Rev., 1947, 71: 270
[5] Ziberi B, Frost F, H?che T, et al.Ripple pattern formation on silicon surfaces by low-energy ion-beam erosion: Experiment and theory[J]. Phys. Rev., 2005, 72B: 235310
[6] Lisfi A, Lodder J C, Wormeester H, et al.Reorientation of magnetic anisotropy in obliquely sputtered metallic thin films[J]. Phys. Rev., 2002, 66B: 174420
[7] Fan X L, Xue D S, Lin M, et al.In situ fabrication of Co90Nb10 soft magnetic thin films with adjustable resonance frequency from 1.3 to 4.9 GHz[J]. Appl. Phys. Lett., 2008, 92: 222505
[8] Yang Y, Liu B L, Tang D M, et al.Influence of the magnetic field annealing on the extrinsic damping of FeCoB soft magnetic films[J]. J. Appl. Phys., 2010, 108: 073902
[9] Viala B, Inturi V R, Barnard J A.Effect of magnetic annealing on the behavior of FeTaN films[J]. J. Appl. Phys., 1997, 81: 4498
[10] Nogués J, Schuller I K.Exchange bias[J]. J. Magn. Magn. Mater., 1999, 192: 203
[11] Phuoc N N, Chai G Z, Ong C K.Enhancing exchange bias and tailoring microwave properties of FeCo/MnIr multilayers by oblique deposition[J]. J. Appl. Phys., 2012, 112: 113908
[12] Acher O, Dubourg S.Generalization of Snoek's law to ferromagnetic films and composites[J]. Phys. Rev., 2008, 77B: 104440
[13] Iakubov I T, Lagarkov A N, Maklakov S A, et al.Microwave permeability of composites filled with thin Fe films[J]. J. Magn. Magn. Mater., 2006, 300: e74
[14] Perrin G, Acher O, Peuzin J C, et al. Sum rules for gyromagnetic permeability of ferromagnetic thin films: Theoretical and experimental results [J]. J. Magn. Magn. Mater., 1996, 157-158: 289
[15] Chai G Z, Phuoc N N, Ong C K.Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film[J]. Sci. Rep., 2012, 2: 832
[16] Wei J W, Zhu Z T, Feng H M, et al.Top-down control of dynamic anisotropy in permalloy thin films with stripe domains[J]. J. Phys., 2015, 48D: 465001
[17] Chai G Z, Phuoc N N, Ong C K.High thermal stability of zero-field ferromagnetic resonance above 5?GHz in ferrite-doped CoFe thin films[J]. Appl. Phys. Lett., 2013, 103: 042412
[18] Zhou C, Wei W W, Jiang C J.Regulated magnetic domains and high-frequency property in magnetic materials with columnar structure[J]. Appl. Phys., 2015, 121A: 39
[19] Singh G, Rout P K, Porwal R, et al.Strain induced magnetic domain evolution and spin reorientation transition in epitaxial manganite films[J]. Appl. Phys. Lett., 2012, 101: 022411
[20] Tee Soh W, Phuoc N N, Tan C Y, et al.Magnetization dynamics in permalloy films with stripe domains[J]. J. Appl. Phys., 2013, 114: 053908
[21] Fin S, Tomasello R, Bisero D, et al.In-plane rotation of magnetic stripe domains in Fe1-xGax thin films[J]. Phys. Rev., 2015, 92B: 224411
[22] Li C Y, Chai G Z, Yang C C, et al.Tunable zero-field ferromagnetic resonance frequency from S to X band in oblique deposited CoFeB thin films[J]. Sci. Rep., 2015, 5: 17023
[23] Yu J, Chang C, Karns D, et al.Thermal annealing effect on FeCoB soft underlayer for perpendicular magnetic recording[J]. J. Appl. Phys., 2002, 91: 8357
[24] Sharma P, Kimura H, Inoue A, et al.Temperature and thickness driven spin-reorientation transition in amorphous Co-Fe-Ta-B thin films[J]. Phys. Rev., 2006, 73B: 052401
[25] Co?sson M, Vinai F, Tiberto P, et al.Magnetic properties of FeSiB thin films displaying stripe domains[J]. J. Magn. Magn. Mater., 2009, 321: 806
[26] Zhan Q F, van Haesendonck C, Vandezande S, et al. Surface morphology and magnetic anisotropy of Fe/MgO(001) films deposited at oblique incidence[J]. Appl. Phys. Lett., 2009, 94: 042504
[27] Wang G X, Dong C H, Wang W X, et al.Observation of rotatable stripe domain in permalloy films with oblique sputtering[J]. J. Appl. Phys., 2012, 112: 093907
[28] Chen Y T, Xie S M.Magnetic and electric properties of amorphous Co40Fe40B20 thin films[J]. J. Nanomater., 2012, 2012: 486284
[29] Saravanan L, Raja M M, Prabhu D, et al.Effect of thickness on tuning the perpendicular coercivity of Ta/CoFeB/Ta trilayer[J]. J. Mater. Sci.: Mater. Electron., 2018, 29: 336
[30] Youssef J B, Vukadinovic N, Billet D, et al.Thickness-dependent magnetic excitations in Permalloy films with nonuniform magnetization[J]. Phys. Rev., 2004, 69B: 170002
[31] Zhou C, Jiang C J, Zhao Z.Enhancement of rotatable anisotropy in ferrite doped FeNi thin film with oblique sputtering[J]. J. Phys., 2015, 48D: 265001
[1] 何贤美, 童六牛, 高成, 王毅超. Nd含量对磁控溅射Si(111)/Cr/Nd-Co/Cr薄膜结构与磁性的影响[J]. 金属学报, 2019, 55(10): 1349-1358.
[2] 何正明;徐舫;罗有泉;卢国荣. 非晶合金带的单轴各向异性[J]. 金属学报, 1991, 27(2): 99-103.
[3] 毕耜云;马小丁;宋瑞田;梅良模;赵见高;郭贻诚. 金属Fe/Cu超晶格的结构和铁磁共振[J]. 金属学报, 1990, 26(5): 131-136.