Manipulation of the coercivity of FeCoCr films through artificial defects engineering based on Bi doping
Manipulation of the coercivity of FeCoCr films through artificial defects engineering based on Bi doping
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基于 Bi 掺杂的人工缺陷工程控制 FeCoCr 薄膜的矫顽力
DOI：
10.1016/j.apsusc.2022.155261
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发表时间：
2023
影响因子：
6.7
通讯作者：
G.H. Yu
中科院分区：
文献类型：
--
作者：
J.T. Liu;X.L. Xu;G. Han;X.Y. Yang;W.X. Ai;W.Y. Hu;J. Teng;B.H. Li;G.H. Yu
FeCoCr薄膜被认为是高精度磁旋转编码器磁码盘材料的理想选择。然而，从实际应用的观点来看，实现具有足够剩磁的高矫顽力对于磁记录稳定性是关键问题。我们采用磁控溅射法在Si衬底上制备了无Bi和Bi掺杂的FeCoCr（250 nm）/Ta（10 nm）薄膜，然后在650 °C下真空退火30 min。无Bi和Bi掺杂的FeCoCr样品的面内矫顽力分别为414 Oe和930 Oe，表明Bi掺杂可以显著提高FeCoCr样品的面内矫顽力。X射线光电子能谱（XPS）分析表明，在高温退火过程中，Bi原子向薄膜表面扩散并升华。正电子湮没谱（PAS）表明，Bi原子的扩散增加了薄膜中的缺陷密度。扫描透射电子显微镜（STEM）分析表明，Bi原子的扩散不仅细化了晶粒，而且使富Fe-Co（α 1相）和富Cr（α 2相）均匀分布。磁力显微镜（MFM）分析观察到，Bi的引入减小了磁畴尺寸，增加了磁畴密度，从而提高了磁性。
FeCoCr thin films have been considered as promising candidates for magnetic code disk materials used in high-precision magnetic rotary encoders. However, realizing high coercivity with a sufficient remanence is a critical issue for magnetic recording stability from the point of view of practical applications. We prepared Bi-free and Bi-doped FeCoCr(250 nm)/Ta(10 nm) films on Si substrates using magnetron sputtering followed by vacuum annealing at 650 °C for 30 min. The in-plane coercivity of Bi-free and Bi-doped FeCoCr samples are 414 Oe and 930 Oe respectively, indicating that the coercivity can be greatly enhanced by Bi doping. X-ray photoelectron spectroscopy (XPS) reveals that Bi atoms diffuse to the film surface and then sublimate during high-temperature annealing process. Positron annihilation spectroscopy (PAS) indicates that the diffusion of Bi atoms increases the density of defects in the film. Scanning transmission electron microscopy (STEM) analysis shows that the diffusion behavior of Bi atoms not only refines the grain size but also results in a uniform distribution of the Fe-Co-rich (α1phase) phase with the Cr-rich (α2phase) phase. Magnetic force microscopy (MFM) analysis observes that the introduction of Bi decreases the magnetic domain size and increases the magnetic domain density resulting in the enhancement of coercivity.