垂直磁各向异性L1_0-Mn_(1.67)Ga超薄膜分子束外延生长与磁性研究  

Perpendicular magnetic properties of ultrathin L1_0-Mn_(1.67)Ga films grown by molecular-beam epitaxy

作　　者：肖嘉星 鲁军[1] 朱礼军[1] 赵建华[1] 

机构地区：[1]中国科学院半导体研究所半导体超晶格国家重点实验室,北京100083

出　　处：《物理学报》2016年第11期264-269,共6页Acta Physica Sinica

基　　金：国家高技术研究发展计划(批准号:2014AA032904);国家重点基础研究发展计划(批准号:2015CB921500);囯家自然科学基金重点项目(批准号:61334006;11304307)资助的课题~~

摘　　要：具有超强垂直磁各向异性的L1_0-Mn_xGa薄膜由于其与半导体材料结构及工艺的高度兼容性而受到广泛关注,其超高垂直磁各向异性能和极低的磁阻尼因子预示着L1_0-Mn_xGa薄膜在高热稳定性自旋电子学器件中将发挥重要作用.而L1_0-Mn_xGa超薄膜对于降低L1_0-Mn_xGa基垂直磁各向异性隧道结中的磁矩翻转临界电流密度有着重要的意义.本文采用分子束外延的方法,在半导体GaAs衬底上成功制备出了一系列不同厚度的L10-Mn_(1.67)Ga薄膜,厚度范围为1—5 nm.生长过程中反射式高能电子衍射原位检测以及X射线衍射结果均表明了其良好的单晶相.磁性测量结果表明,厚度在1 nm以上的L1_0-Mn_(1.67)Ga薄膜均可以保持垂直磁各向异性特征,厚度为5 nm的L1_0-Mn_(1.67)Ga薄膜的垂直磁各向异性能可达到14.7 Merg/cm^3.这些结果为基于L1_0-Mn_(1.67)Ga的垂直磁各向异性隧道结在自旋转移扭矩驱动的磁随机存储器等低功耗器件的集成及应用提供了重要的实验支持.Materials with large perpendicular magnetic anisotropies（PMAs） have drawn great attention because of their potential applications in advanced spintronic devices such as spin-transfer-torque magnetic random access memory（STTMRAM） and ultrahigh-density perpendicular magnetic recording.To date,a large variety of PMA materials have been investigated,such as L10-ordered Fe Pt,Co Pt granular films,Co/（Pt,Pd,Ni） multilayers,ultra-thin CoFeB alloys and perpendicularly magnetized Co2FeAl films.Among the various kinds of materials with PMA,Mn Ga film with L10-structure has received the most attention because it has large PMA（Ku 107erg/cm3）,ultralow Gilbert damping constant（0.008） and theoretically predicted high spin polarization（more than 70%）.All these properties make L10-ordered Mn Ga a good candidate for spintronic devices such as STT-MRAM and spin-torque oscillators.Meanwhile,from the viewpoint of STT related spintronic device,it is necessary to fabricate ultrathin perpendicularly magnetized L10-MnxGa films to lower the critical current for magnetization reversal.However,up to now,in the main researches the ultrathin L10-MnxGa films have been grown on Mg O substrates,which makes it difficult to integrate the Mn Ga-based magnetic tunnel junctions into the semiconductor manufacturing process.In this work,ultrathin L10-Mn（1.67） Ga films with different thickness values（1–5 nm） are grown on traditional Ga Aa（001） substrates by a molecule-beam epitaxy system.During the deposition,in situ streaky surface reconstruction patterns are observed from reflection high-energy electron diffraction,which implies high crystalline quality of the L10-Mn（1.67） Ga film.Only Mn Ga superlattice（001） and Mn Ga fundamental（002） peaks can be observed in the X-ray diffraction patterns in a range from 20？to 70？,which means that the L10-Mn（1.67） Ga film is a good single-crystalline with c-axis along the normal direction.The magnetic properties of these films are measured by superconductor q

关 键 词：分子束外延 自旋电子学 磁各向异性 超薄膜 

分 类 号：O484.43[理学—固体物理]