磁记录介质用四角形变FeCo薄膜的制备及应力影响研究

Recently, Bct FeCo alloy has drawn much attention and research because of its very high uniaxial magnetic anisotropy energy Ku and saturation magnetization Ms. but it is very difficult to prepare Bct FeCo with high uniaxial magnetic anisotropy energy Ku in experiment. This project is trying to find an easier method for preparing Bct FeCo film. The Bct FeCo film with uniaxial magnetic anisotropy energy Ku will be prepared by inducing thermal stress and external stress. The NaCl single crystal substrate will used to deposit the films at vary temperature, it will cause vary thermal stress because of the large difference of expansion coefficient between substrate and films. The external stress will be induced by depositing the films at a curved surface of a flexible substrate which bended by using a special substrate holder. We will choose Capton VN as a flexible substrate because of its excellent performance such as ultimate elongation (72% at R.T), high temperature resistance (400oC), etc. The different external stress will be attained with different transformation. Finally, we will study the mechanism of stress dependence on Bct FeCo films preparation process

Bct FeCo材料因其有其他磁性材料无法比拟的高磁晶各向异性能Ku和高的饱和磁化强度Ms而引起了广泛关注与研究，但是实验上很难实现。本项目我们将尝试寻找一种比较容易的方法制备Bct FeCo薄膜。我们将采用引入热应力和外应力的方法来制备垂直各向异性的Bct FeCo薄膜。我们将采用NaCl等单晶基片在不同的沉积温度下制备Bct FeCo薄膜，从而引入不同大小的热应力,这是因为两者的热膨胀系数差别很大。对于外应力引入,我们借助于在预先制备的特殊基片架使得柔性基片变形为球面的一部分上沉积薄膜来实现。柔性基片我们将选用性能优异的Capton VN,比如极限伸长量（室温下72%），耐高温性（400摄氏度）等。不同的形变量对应不同的外应力大小。最后，我们将分析研究应力对于Bct FeCo薄膜制备过程的影响机理。

四角形变的（Bct）FeCo薄膜材料理论上具有非常高的饱和磁化强度Ms和非常高的磁晶各向异性能Ku，但实验上制备很困难具有较高磁晶各向异性能的Bct FeCo 薄膜。本项目我们将尝试寻找比较容易的方法制备Bct FeCo薄膜，采用的方法为引入热应力和外力的方法。（1）热应力的引入：在热膨胀系数差别较大的玻璃基片和NaCl单晶基片上分别制备CrRu/Rh/FeCo/Rh薄膜对比研究，发现相同条件下， NaCl单晶基片上制备的薄膜的磁晶各向异性能Ku都大于玻璃基片上制备的薄膜，且磁晶各向异性能Ku随FeCo层厚度的增加而减小，表明热应力的引入可以有效增加磁晶各向异性能Ku。（2）外应力的引入：在预弯曲的Capton VN基片上制备Cr90Ru10/Rh/FeCo/Rh薄膜，结果表明，随着形变量的增加，磁晶各向异性能Ku增加，外应力的引入可以有效增加磁晶各向异性能Ku。