强磁场对不同厚度Fe-Ni纳米多晶薄膜的生长过程及磁性能的影响

Effects of high magnetic field on the growth and magnetic properties of Fe-Ni nano-polycrystalline thin films with different thickness values

有无6 T强磁场条件下,利用分子束气相沉积方法制备了21 nm和235 nm厚的Fe-Ni纳米多晶薄膜.研究发现,0 T时,21 nm厚的薄膜是晶粒堆叠而成,晶粒尺寸为6—7 nm;6 T时,21 nm厚的薄膜首先在基片表面形成了晶粒相互连接的5 nm平坦层,晶粒沿基片表面拉长,随后以6—7 nm尺寸的晶粒堆叠而成;0 T时,235 nm厚度的薄膜生长初期平均晶粒尺寸为3.6 nm,生长中期平均晶粒尺寸为5.6 nm,生长末期薄膜近似柱状方式生长,晶粒沿生长方向拉长;6 T时,235 nm厚度的薄膜在基片表面也形成了晶粒相互连接的5 nm平坦层,晶粒沿基片表面拉长,随后以尺寸均匀的6.1 nm晶粒堆叠而成;而且,6 T强磁场使得不同厚度薄膜的面外与面内矫顽力都降低.

The Fe-Ni nano-polycrystalline thin films of 21 nm and 235 nm in thickness are prepared by molecular beam vapor deposition in the absence and the presence of a magnetic field as high as 6 T. The results show that in the absence of the magnetic field, the 21-nm-thick thin films are formed by the grain stacks, and the sizes of grains are about 6-7 nm. In the presence of 6 T, the 5-nm-thick fiat layers of interconnected grains of 21-nm-thick thin films are first formed on the surfaces of the substrates, and the grains are then elongated along the surfaces of substrates. Later on, the 21-nm-thick thin films are formed by 6-7 nm-size-grain stacks. In the absence of the magnetic field, the average grain size of the 235-nm-thick thin film is 3.6 nm in the early growth stage, and it is 5.6 nm in the middle growth stage. The growth way of thin film is akin to columnar growth in the final growth stage, and the grains are elongated along the growth direction. In the presence of 6 T, the 5-nm-thick flat layers of interconnected grains of 235-nm-thick thin films are also formed on the surfaces of the substrates, and the grains are elongated along the surfaces of substrates. Later on, the 235-nm-thick thin films are formed by about 6.1-nm-size-grain stacks. Accordingly, the coercive forces in the out-of-plane and in the in-plane of thin films of different thickness values decrease by the 6 T magnetic field.