报告内容：GaMnAs is a widely investigated ferromagnetic semiconductor, holding significant promise for spintronic applications. It is now well established that strain effects play an important role in determining the magnetic anisotropy of epitaxial III-Mn-V films. Specifically, the magnetic easy axis of GaMnAs films grown GaAs substrates lies in the film plane because of the compressive strain in the film. However, replacing a small fraction of As by P is known to change the strain to tensile, leading to an out-of-plane orientation of the magnetic easy axis. In this talk, we investigate the effect of grading the concentration of P along the growth direction in this quaternary alloy. A graded (Ga0.94Mn0.06)(As1-xPx) film has been grown by low-temperature molecular beam epitaxy. Although there are 8 layers with different content of P, the specimen shows only one Curie temperature and the magnetic properties shown from the magnetization vs. magnetic field curves also behave like a single-phase film, indicating that the eight layers are magnetically coupled with each other. Most interestingly, the magnetic easy axis is remains in the film plane instead of normal to the film. These results suggest that one can design ferromagnetic semiconductor structures with different types of magnetic anisotropy by such graded strain effects. In this talk, I will also give a general introduction about our molecular beam epitaxy facility and various kinds of materials we are growing.
报告人简介：美国圣母大学(University of Notre Dame)博士后研究员(2013年至今), 美国阿贡国家实验室材料科学部兼职研究员(2016年至今)。本科及博士毕业于中国科学技术大学(2003～2012年)。研究领域包括分子束外延在内的多项薄膜生长技术、薄膜的微纳加工技术和自旋电子器件的相关研究。