Fabrication of perpendicular magnetized tunnel junction and magnetization reversal by spin injection

为了开发适用于高密度磁性随机存取存储器（MRAM）的存储单元材料，研究了饱和磁化强度Ms、垂直磁各向异性常数Ku和吉尔伯特阻尼常数对材料组成的依赖性。在外延Mn_xGa_<1-x>（0. 500万x 100万。75)合金薄膜随着x的增加，M_s值从600 ~ 200 emu/cc线性下降，而K_u值从15 ~ 10 Merg/cc略有下降。阻尼常数。是0。08（0. 015)Mn_<1. 54>Ga（Mn_<2. 12>Ga）薄膜。此外，我们还研究了Mn-Ga合金薄膜作为隧道结电极在10 K和300 K下的磁电阻比。在Mn-Ga电极和隧道势垒之间插入Fe（Co）后，室温下的TMR值最高可达60（40）%。MRAM存储单元需要增加TMR值。

In order to develop a memory cell material which is applicable to high density magnetic random access memory (MRAM), the composition dependence on saturation magnetization Ms, perpendicular magnetic anisotropy constant Ku and Gilbert damping constant . have been investigated in epitaxial Mn_xGa_<1-x> (0. 5≦x≦0. 75)alloy films. The M_s values decrease linearly from approximately 600 to 200 emu/cc with increasing x, where as the K_u values decrease slightly from 15 to 10 Merg/cc with increasing x. The damping constant . is 0. 08 (0. 015)for Mn_<1. 54> Ga (Mn_<2. 12> Ga)film. These magnetic properties satisfy the requirement for memory cell.Furthermore, by using Mn-Ga alloy films as the electrode of tunnel junction, we investigated the magnetoresistance ratio at 10 K and 300 K. With an insertion of Fe (Co)between Mn-Ga electrode and tunnel barrier the maximum TMR value up to 60 (40)%is obtained at room temperature. An increase of TMR value is necessary for MRAM memory cell.