Effect of Nd Content on the Structure and Magnetic Properties of Si(111)/Cr/Nd-Co/Cr Thin Films Prepared by Magnetron Sputtering
Received date: 2018-10-30
Revised date: 2019-06-24
Online published: 2019-07-26
Supported by
Supported by National Natural Science Foundation of China(51671001)
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 NdCo5±x 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 NdCo5±x and Nd2Co7 nanocrystals, while that of the samples with x>4.4 remained low value (Hc-in=4~8 kA/m).
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[J]. Acta Metall Sin, 2019 , 55(10) : 1349 -1358 . DOI: 10.11900/0412.1961.2018.00490
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