Shirsath Sagar E, Liu Xiaoxi, Yasukawa Yukiko, Li Sean, Morisako Akimitsu
Spin Device Technology Center, Faculty of Engineering, Shinshu University, Nagano 380-8553, Japan.
School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2502, Australia.
Sci Rep. 2016 Jul 20;6:30074. doi: 10.1038/srep30074.
Perpendicular magnetization and precise control over the magnetic easy axis in magnetic thin film is necessary for a variety of applications, particularly in magnetic recording media. A strong (111) orientation is successfully achieved in the CoFe2O4 (CFO) thin film at relatively low substrate temperature of 100 °C, whereas the (311)-preferred randomly oriented CFO is prepared at room temperature by the DC magnetron sputtering technique. The oxygen-deficient porous CFO film after post-annealing gives rise to compressive strain perpendicular to the film surface, which induces large perpendicular coercivity. We observe the coercivity of 11.3 kOe in the 40-nm CFO thin film, which is the highest perpendicular coercivity ever achieved on an amorphous SiO2/Si substrate. The present approach can guide the systematic tuning of the magnetic easy axis and coercivity in the desired direction with respect to crystal orientation in the nanoscale regime. Importantly, this can be achieved on virtually any type of substrate.
对于各种应用，特别是在磁记录介质中，垂直磁化以及对磁性薄膜中易磁化轴的精确控制是必要的。在100°C的相对较低衬底温度下，CoFe2O4（CFO）薄膜成功实现了强烈的（111）取向，而在室温下通过直流磁控溅射技术制备了（311）择优随机取向的CFO。退火后的缺氧多孔CFO薄膜会产生垂直于薄膜表面的压缩应变，这会导致较大的垂直矫顽力。我们在40nm的CFO薄膜中观察到11.3kOe的矫顽力，这是在非晶SiO2/Si衬底上实现的最高垂直矫顽力。本方法可以在纳米尺度范围内，相对于晶体取向，将易磁化轴和矫顽力系统地调整到所需方向。重要的是，这几乎可以在任何类型的衬底上实现。
