具有表面周期结构的柔性磁性薄膜的磁各向异性及其高频磁性研究

Magnetic anisotropy of magnetic films determines the working frequency of high-frequency magnetic devices using them. With the development of electronic device towards the flexibility and high frequency, the control of magnetic anisotropy in flexible magnetic films and their application in high-frequency devices have attracted extensive attentions. Due to the elasticity mismatch at the interface, the flexible magnetic films grown on stretching polydimethylsiloxane (PDMS) substrate display a stretchable periodically wrinkled topography, which leads to the origin of magnetic anisotropy and their controlling method remarkably different from that in conventional flat films. In this project, we propose to select the soft magnetic alloys such as FeCoTa, and investigate the effect of growth processes and the properties of metallic materials on the wrinkled topography, the stripe domain structure, the magnetic anisotropy, and the high-frequency magnetic behaviors of flexible magnetic films grown on PDMS. We may know how to employ the oblique deposition to improve the magnetic anisotropy and the high-frequency magnetic property in flexible wrinkled magnetic films. We propose to study the mechanism of stress relief in the wrinkled surface structure, thus to obtain flexible magnetic films with the stable magnetic anisotropy and high-frequency magnetic behavior even when stretching. We will clarify the contribution of stress-induced magnetic anisotropy and surface magnetic anisotropy on the total magnetic anisotropy. By means of constructing a model for surface magnetic anisotropy based on the distribution of magnetic charges, we may understand the origin of magnetic films in flexible magnetic films. Our investigation may provide the necessary fundamental knowledge and the potential magnetic films for the development of flexible high-frequency magnetic devices in future.

磁性薄膜的磁各向异性决定了高频磁性器件的工作频率，随着电子器件的柔性化和高频化的发展需求，柔性磁性薄膜的磁各向异性控制及其在高频器件中的应用得到了广泛的关注。生长在聚二甲基硅氧烷（PDMS）上的柔性磁性薄膜由于界面力学失稳，从而具有可拉伸的表面周期结构，使得其磁各向异性的调控与起源有别于传统的平整薄膜。本项目中，我们拟选择FeCoTa等软磁合金，研究制备工艺、材料属性对生长在PDMS衬底上的柔性磁性薄膜的表面周期结构、条纹磁畴、磁各向异性、高频磁性的影响规律，掌握倾斜生长对具有表面周期结构的柔性磁性薄膜的磁各向异性与高频磁性的调控机制。研究表面周期结构的应力释放机制，获得拉伸状态下磁各向异性与高频磁性保持稳定的柔性磁性薄膜。研究表面磁各向异性与应力磁各向异性的贡献，建立基于磁荷分布的表面磁各向异性模型，理解柔性磁性薄膜中磁各向异性的起源。为未来柔性高频磁性器件的开发提供技术储备与理论基础。

磁性薄膜的磁各向异性决定了高频磁性器件的工作频率，随着电子器件的柔性化和高频化的发展需求，柔性磁性薄膜的磁各向异性控制及其在高频器件中的应用得到了广泛的关注。生长在聚二甲基硅氧烷（PDMS）上的柔性磁性薄膜由于界面力学失稳，从而具有可拉伸的表面周期结构，使得其磁各向异性的调控与起源有别于传统的平整薄膜。本项目中，我们研究了倾斜溅射对CoFeB薄膜条纹磁畴结构与磁各向异性的调控规律；利用应力磁各向异性与条纹畴转动磁各向异性，突破了Snoek极限，有效提高了柔性FeGa薄膜的铁磁共振频率并保持起始磁导率不显著下降。通过褶皱条带结构有效释放拉伸应力，获得了目前报道的最高50%可拉伸性的柔性巨磁电阻自旋阀传感薄膜结构。掌握了具有“之”字型表面周期结构的磁性薄膜的制备方法，获得了具有不同磁各向异性、交换偏置特性的柔性NiFe薄膜和NiFe/IrMn双层膜。自主搭建了国内首套柔性高频磁性测量系统，掌握了衬底预应变和倾斜生长对具有表面周期结构的柔性FeCoTa薄膜磁各向异性与高频磁性的影响规律。获得了拉伸应变对具有表面周期结构的柔性CoFeB薄膜高频磁性的调控规律，通过降低泊松比产生的裂纹，提高了柔性CoFeB薄膜高频磁性在拉伸应变下的稳定性。我们的研究可以为未来柔性高频磁性器件的开发提供技术储备与理论基础。在项目资助下，我们以通讯作者发表SCI论文10篇，以非通讯作者发表SCI论文1篇。