Ranjbar Reza, Suzuki Kazuya, Sugihara Atsushi, Miyazaki Terunobu, Ando Yasuo, Mizukami Shigemi
WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan.
Materials (Basel). 2015 Sep 22;8(9):6531-6542. doi: 10.3390/ma8095320.
Synthetic perpendicular magnetic anisotropy (PMA) ferrimagnets consisting of 30-nm-thick D0-MnGa and Co₂MnSi (CMS) cubic Heusler alloys with different thicknesses of 1, 3, 5, 10 and 20 nm, buffered and capped with a Cr film, are successfully grown epitaxially on MgO substrate. Two series samples with and without post annealing at 400 °C are fabricated. The (002) peak of the cubic L2₁ structure of CMS films on the MnGa layer is observed, even for the 3-nm-thick CMS film for both un-annealed and annealed samples. The smaller remnant magnetization and larger switching field values of CMS (1-20 nm)/MnGa (30 nm) bilayers compared with 30-nm-thick MnGa indicates antiferromagnetic (AFM) interfacial exchange coupling (J) between MnGa and CMS films for both un-annealed and annealed samples. The critical thickness of the CMS film for observing PMA with AFM coupling in the CMS/MnGa bilayer is less than 10 nm, which is relatively large compared to previous studies.
由30纳米厚的D0-MnGa和不同厚度（1、3、5、10和20纳米）的Co₂MnSi（CMS）立方赫斯勒合金组成，并由Cr膜缓冲和覆盖的合成垂直磁各向异性（PMA）亚铁磁体，成功地在MgO衬底上外延生长。制备了有和没有在400°C下进行后退火的两个系列样品。即使对于未退火和退火样品中3纳米厚的CMS膜，也观察到了MnGa层上CMS膜立方L2₁结构的（002）峰。与30纳米厚的MnGa相比，CMS（1-20纳米）/MnGa（30纳米）双层具有更小的剩余磁化强度和更大的开关场值，这表明未退火和退火样品中MnGa与CMS膜之间存在反铁磁（AFM）界面交换耦合（J）。在CMS/MnGa双层中观察到具有AFM耦合的PMA的CMS膜的临界厚度小于10纳米，与先前的研究相比相对较大。
