厚度对M型钡铁氧体薄膜结构及磁性能的影响

摘要

采用射频(RF)磁控溅射法在蓝宝石基片上制备M型钡铁氧体(BaM)薄膜,研究了薄膜厚度对BaM铁氧体薄膜的结构及磁性能影响.结果显示,样品的衍射峰全部为BaM薄膜的(00l)衍射峰,表明样品都具有良好的c轴取向性.显微结构分析结果表明,在膜厚为40~90nm范围内,薄膜样品表面主要为c轴取向的片状晶粒,未出现c轴随机取向的针状晶粒;当样品厚度增加至140nm时,出现了较明显的针状晶粒;随着薄膜厚度进一步增加到190nm时,样品表面出现了大量c轴随机取向的针状晶粒,且部分针状晶粒长度达到了μm级.磁性能测试结果显示,随着薄膜厚度的增加,薄膜样品饱和磁化强度降低,垂直膜面方向矫顽力和剩磁比减小,膜厚40~90nm范围的薄膜在垂直膜面方向获得了最大剩磁比和矫顽力,表现出较好的磁晶各向异性.%M-type barium ferrite (BaM) films with different thicknesses have been deposited on the sapphire substrates by radio frequency (RF) magnetron sputtering technique. Influence of film thickness on the microstructure and magnetic properties of BaM films has been investigated. The structure and magnetic properties of films were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM) and vibrating sample magneto- meter (VSM), respectively. XRD data indicates that all samples exhibit(00l)diffraction peak, showing good c-axis orientation. For thickness ranging from 40nm to 90nm, BaM films mainly form lamellar grains with good c-axis orientation. However, apparent needle-like grains appear as the thickness is larger than 90nm. When the thickness is 190nm, the grain size for part of the needle-like grains even achieves the magnitude order of micron. VSM test results show that as the thickness of sample increases, the saturation magnetization of the film sample reduces, the coercivity and the remanence ratio perpendicular to the film plane decreases. When the thickness changes from 40nm to 90nm, BaM films obtain the largest coercivity and remanence ratio in the direction perpendicular to the film plane and show good magnetic anisotropy.