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金属学报  2019, Vol. 55 Issue (10): 1349-1358    DOI: 10.11900/0412.1961.2018.00490
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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
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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    

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  
通讯作者: 童六牛     E-mail:
Corresponding author: Liuniu TONG     E-mail:
作者简介: 何贤美,女,1963年生,副教授


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.

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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
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