Please wait a minute...
金属学报  2019, Vol. 55 Issue (10): 1349-1358    DOI: 10.11900/0412.1961.2018.00490
  本期目录 | 过刊浏览 |
Nd含量对磁控溅射Si(111)/Cr/Nd-Co/Cr薄膜结构与磁性的影响
何贤美1,童六牛2(),高成2,王毅超2
1. 安徽工业大学数理科学与工程学院 马鞍山 243002
2. 安徽工业大学材料科学与工程学院 马鞍山 243002
Effect of Nd Content on the Structure and Magnetic Properties of Si(111)/Cr/Nd-Co/Cr Thin Films Prepared by Magnetron Sputtering
HE Xianmei1,TONG Liuniu2(),GAO Cheng2,WANG Yichao2
1. School of Mathematics and Physics, Anhui University of Technology, Ma'anshan 243002, China
2. School of Materials Science and Engineering, Anhui University of Technology, Ma'anshan 243002, China
全文: PDF(19580 KB)   HTML
摘要: 

采用磁控溅射技术制备了系列Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜,其中,Co/Nd原子比x=2.5~7.2。利用XRD、SEM、AFM/MFM、VSM等手段研究了Nd含量对制备态薄膜垂直磁各向异性(PMA)与磁畴结构及退火态薄膜相结构与磁性的影响规律。结果表明,随着Nd含量的变化,制备态Nd-Co薄膜的垂直磁各向异性能Kux=5.2附近存在一个较宽的峰,峰值处Ku=(80±5) kJ/m3。MFM图像的相移均方根偏差(Δ?rms)在临界成分x=5.2处也存在最大值,其成分依赖关系与Ku-x的变化趋势一致。薄膜应力诱导的磁弹各向异性是导致溅射Nd-Co非晶薄膜PMA的主要原因。经过在600 ℃真空快速退火后,所有薄膜均析出了Nd2Co17、NdCo2、Nd4Co3等金属间化合物,而NdCox相纳米晶只在Nd过量(至少4%,原子分数)的x=2.5和3.8薄膜中才被观测到,同时还伴随着Nd2Co7共生相的析出。室温磁性测试结果表明,NdCox和Nd2Co7相纳米晶的析出,导致x=2.5和3.8薄膜面内矫顽力(分别为Hc-in=54和51 kA/m)显著增强;而x≥4.4样品的面内矫顽力保持在低值(Hc-in=4~8 kA/m)范围内。

关键词 磁性薄膜垂直磁各向异性稀土-过渡族金属合金NdCo5金属间化合物条纹磁畴    
Abstract

A series of Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm) thin films with the atomic ratio of Co/Nd (x) varying from 2.5 to 7.2 were prepared by radio frequency magnetron sputtering. The influence of Nd content on the structure and magnetic properties of the as-prepared and post annealed films were investigated by XRD, SEM, VSM and AFM/MFM. Magnetic measurements at room temperature show that the compositional variation of the perpendicular anisotropy energy (Ku) exhibits a broad peak around x=5.2 with maximum of Ku=(80±5) kJ/m3 for the as-prepared Nd-Co amorphous films. MFM characterization shows that the root mean square deviation of phase shift in MFM images (Δ?rms) also have a compositional dependence which is similar to that of Ku-x. The experimental results show that the stress induced magneto-elastic anisotropy is the primary origin of the perpendicular magnetic anisotropy (PMA) in the as-prepared Nd-Co amorphous film. After rapid thermal annealing (RTA) process in a vacuum atmosphere at 600 °C, intermetallic compounds such as Nd2Co17, Nd4Co3 and NdCo2 are precipitated in all the studdied films, while NdCox nanocrystals accompanied by the precipitation of Nd2Co7 symbiotic phase were observed only in the films with x=2.5 and 3.8 (the atomic fraction of Nd excesses at least 4%). The in-plane coercivity of the films with x=2.5 and 3.8 was significantly enhanced (Hc-in=54, 51 kA/m) due to the precipitation of NdCox and Nd2Co7 nanocrystals, while that of the samples with x>4.4 remained low value (Hc-in=4~8 kA/m).

Key wordsmagnetic thin film    perpendicular magnetic anisotropy    rare-earth-transition-metal alloy    NdCo5 intermetallic compound    striped magnetic domain
收稿日期: 2018-10-30     
ZTFLH:  TM271  
基金资助:国家自然科学基金项目(51671001)
通讯作者: 童六牛     E-mail: lntong@ahut.edu.cn
Corresponding author: Liuniu TONG     E-mail: lntong@ahut.edu.cn
作者简介: 何贤美,女,1963年生,副教授

引用本文:

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.
Xianmei HE, Liuniu TONG, Cheng GAO, Yichao WANG. Effect of Nd Content on the Structure and Magnetic Properties of Si(111)/Cr/Nd-Co/Cr Thin Films Prepared by Magnetron Sputtering. Acta Metall Sin, 2019, 55(10): 1349-1358.

链接本文:

https://www.ams.org.cn/CN/10.11900/0412.1961.2018.00490      或      https://www.ams.org.cn/CN/Y2019/V55/I10/1349

图1  制备态Si(111)/Cr(10 nm)/NdCox (400 nm)/Cr(10 nm)薄膜的XRD谱
图2  制备态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的面内与法向磁滞回线
图3  制备态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的饱和磁化强度(Ms)和平面内饱和磁化场(Hs-in),及有效磁各向异性能(Keff)、形状各向异性能(Kd)和磁弹性各向异性能(Kme)随x的变化
图4  制备态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的MFM像
图5  制备态薄膜的单轴磁各向异性常数(Ku)和MFM像相移的均方根偏差(Δ?rms)随x的变化曲线
图6  制备态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的MFM和AFM像
图7  制备态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm) 薄膜中Co和Nd元素的二维成分分布图
图8  制备态Si(111)/Cr(10 nm)/NdCo5.2 (400 nm)/Cr(10 nm)薄膜分别经过在不同退火温度(Ta)真空退火后的面内磁滞回线,及面内矫顽力(Hc-in)和剩磁比(Mr/Ms)随Ta的变化关系
图9  在600 ℃快速退火30 min后Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的XRD谱
图10  经600 ℃快速退火30 min后Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的室温磁滞回线
图11  室温下测定的退火态Si(111)/Cr(10 nm)/NdCox(400 nm)/Cr(10 nm)薄膜的Hc-in随x的变化关系
[1] Bhatti S, Sbiaa R, Hirohata A ,et al. Spintronics based random access memory: A review [J]. Mater. Today, 2017, 20: 530
[2] Wang M X, Cai W L, Cao K H, et al. Current-induced magnetization switching in atom-thick tungsten engineered perpendicular magnetic tunnel junctions with large tunnel magnetoresistance [J]. Nat. Commun., 2018, 9: 671
[3] Dai B, Guo Y, Zhu J Q, et al. Spin transfer torque switching in exchange-coupled amorphous GdFeCo/TbFe bilayers for thermally assisted MRAM application [J]. J. Phys., 2017, 50D: 135005
[4] Nakayama M, Kai T, Shimomura N ,et al. Spin transfer switching in TbCoFe/CoFeB/MgO/CoFeB/TbCoFe magnetic tunnel junctions with perpendicular magnetic anisotropy [J]. J. Appl. Phys., 2008, 103: 07A710
[5] Zhang W Y, Shima H, Takano F, et al. Origin of perpendicular magnetic anisotropy and evolution of magnetic domain structure of amorphous Pr-TM-B (TM=Fe, Co) films [J]. J. Magn. Magn. Mater., 2010, 322: 900
[6] Hansen P, Raasch D, Mergel D. Magnetic and magneto-optical properties of amorphous rare earth-transition-metal alloys containing Pr, Nd, Fe, Co [J]. J. Appl. Phys., 1994, 75: 5267
[7] Anjum S, Rafique M S, Khaleeq-ur-Rahman M ,et al. Magnetic and optical properties of amorphous NdFeCo thin films by pulsed laser deposition technique [J]. Vacuum, 2010, 85: 126
[8] Xi L, Li X Y, Zhou J J ,et al. Influence of magnetic annealing on high-frequency magnetic properties of FeCoNd films [J]. Mater. Sci. Eng., 2011, B176: 1317
[9] Chaudhari P, Cuomo J J, Gambino R J. Amorphous metallic films for magneto-optic applications [J]. Appl. Phys. Lett., 1973, 22: 337
[10] Suzuki Y, Takayama S, Kirino F ,et al. Single ion model for perpendicular magnetic anisotropy in RE-TM amorphous films [J]. IEEE Trans. Magn., 1987, 23: 2275
[11] Fu H, Mansuripur M, Meystre P. Generic source of perpendicular anisotropy in amorphous rare-earth-transition-metal films [J]. Phys. Rev. Lett., 1991, 66: 1086
[12] Harris V G, Pokhil T. Selective-resputtering-induced perpendicular magnetic anisotropy in amorphous TbFe films [J]. Phys. Rev. Lett., 2001, 87: 067207
[13] Harris R, Pilschke M, Zukermann M J. New model for amorphous magnetism [J]. Phys. Rev. Lett., 1973, 31: 160
[14] Cid R, Rodríguez-Rodríguez G, álvarez-Prado L M ,et al. Temperature dependence of the anisotropy of amorphous NdCo5 thin films [J]. J.Magn. Magn. Mater., 2007, 316: e446
[15] Cid R, Díaz J, álvarez-Prado L M ,et al. Microscopic origin of perpendicular magnetic anisotropy in amorphous Nd-Co homogeneous and compositionally modulated, thin films studied by XMCD [J]. J. Phys., 2010, 200: 072017
[16] Ohta M, Yamada K, Satake Y ,et al. Origin of perpendicular magnetic anisotropy in Tb-Fe amorphous alloy [J]. Mater. Trans., 2003, 44: 2605
[17] Xi L, Lu J M, Zhou J J ,et al. Thickness dependence of magnetic anisotropic properties of FeCoNd films [J]. J. Magn. Magn. Mater., 2010, 322: 2272
[18] Yu Y X, Yang Y R, Shan Y J, et al. Abnormal substrate temperature dependent out-of-plane anisotropy in FeCoNbB amorphous films [J]. Appl. Phys. Lett., 2012, 101: 232408
[19] Tong L N, Li T T, He X M ,et al. The effects of the growth pressure and annealing conditions on perpendicular magnetic anisotropy of sputtered NdFeCo films on Si (111) [J]. J. Alloys Compd., 2014, 605: 149
[20] Tong L N, Deng P, He X M ,et al. Abnormal effect of substrate temperature on perpendicular magnetic anisotropy in sputter-deposited NdFeCo films on silicon substrates [J]. Thin Solid Films, 2014, 562: 543
[21] Sharma P, Kimura H, Inoue A. Observation of unusual magnetic behavior: Spin reorientation transition in thick Co-Fe-Ta-B glassy films [J]. J. Appl. Phys., 2006, 100: 083902
[22] Hubert A, Sh?fer R. Magnetic Domains: The Analysis of Magnetic Microstructures [M]. Berlin: Springer, 1998: 238
[23] Co?son M, Celegato F, Olivetti E ,et al. Stripe domains and spin reorientation transition in Fe78B13Si9 thin films produced by RF sputtering [J]. J. Appl. Phys., 2008, 104: 033902
[24] Xia A L, Zhang H L, Tong L N ,et al. Lattice mismatch induced weak perpendicular anisotropy in Fe/Co multilayers prepared by direct current magnetron sputtering [J]. Thin Solid Films, 2008, 516: 7653
[25] Johnson M T, Bloemen P J H, Den Broeder F J A ,et al. Magnetic anisotropy in metallic multilayers [J]. Rep. Prog. Phys., 1996, 59: 1409
[26] Hamann J E, Mohanan S, Herr U. A method for applying a large persistent in-plane biaxial stress to influence the perpendicular magnetic anisotropy of magnetic thin films [J]. J. Appl. Phys., 2007, 102: 113910
[27] Jeong J R, Kim Y S, Shin S C. Origins of perpendicular magnetic anisotropy in Ni/Pd multilayer films [J]. J. Appl. Phys., 1999, 85: 5762
[28] Dai D S, Qian K M. Ferromagnetism (Book 1) [M]. 2nd Ed., Beijing: Science Press, 2018: 174
[28] (戴道生, 钱昆明. 铁磁学(上册) [M]. 第2版. 北京: 科学出版社, 2018: 174)
[29] Hierro-Rodriguez A, Cid R, Vélez M, et al. Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy [J]. Phys. Rev. Lett., 2012, 109: 117202
[30] Taylor R C, McGuire T R, Coey J M D ,et al. Magnetic properties of amorphous neodymium-transition-metal films [J]. J. Appl. Phys., 1976, 49: 2885
[31] Akdogan N G, Li W F, Hadjipanayis G C. Novel NdCo5 nanoflakes and nanoparticles produced by surfactant-assisted high-energy ball milling [J]. J. Nanopart. Res., 2012, 14: 719
[32] Seifert M, Schultz L, Neu V. Magnetization processes and spin reorientation in epitaxial NdCo5±x thin films [J]. J. Appl. Phys., 2009, 106: 073915
[33] Seifert M, Schultz L, Neu V. Investigation of the c-axis and basal plane anisotropy in epitaxial NdCo5 thin films [J]. J. Appl. Phys., 2010, 107: 09A711
[34] Yang Y Q, Rao G H, Wang T ,et al. Effects of Fe substitution on structural and magnetic properties of the Nd2Co7-xFexcompounds [J]. J. Alloys Compd., 2010, 506: 766
[35] Liu X B, Du Z M, Guo C P ,et al. Thermodynamic assessment of the Co-Nd system [J]. J. Alloys Compd., 2007, 439: 97
[1] 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.
[2] 代由勇; 刘宜华; 萧淑琴; 张林; 吴厚政; 张延忠 . Fe-Cu-Cr-V-Si-B三明治膜的巨磁阻抗效应[J]. 金属学报, 2001, 37(3): 277-280 .
[3] 余晋岳; 魏福林 . 微型NiFe磁性薄膜元件中Neel畴壁极性的转变过程[J]. 金属学报, 2000, 36(4): 359-363 .
[4] 邹志强;李明;蒋志红;罗才卿;沈德芳. Tb/Co成分调制膜的磁、磁光性能和热稳定性[J]. 金属学报, 1997, 33(7): 749-755.
[5] 江海;武庆兰;陶琨;李恒德. 离子束辅助沉积Fe-N薄膜的相形成[J]. 金属学报, 1994, 30(18): 273-276.