Chen Ting, Wang Junhao, Cheng Zhenxiang, Wang Xiaotian, Chen Hong
School of Physical Science and Technology, Southwest University, Chongqing, 400715, People's Republic of China.
Institute for Superconducting & Electronic Materials (ISEM), University of Wollongong, Wollongong, 2500, Australia.
Sci Rep. 2018 Nov 8;8(1):16530. doi: 10.1038/s41598-018-34881-y.
Directly coupled hard and soft ferromagnets were popularly used as the hybridized electrodes to enhance tunnel magnetoresistance (TMR) ratio in the perpendicular magnetic tunnel junction (pMTJ). In this paper, we employ the density functional theory (DFT) with general gradient approximation (GGA) to investigate the interfacial structure and magnetic behavior of tetragonal Heusler-type MnGa (MG)/L2-CoMnSi (CMS) Heusler alloy bilayers with the MnGa being D0-MnGa alloy (MnGa) and L1-MnGa alloy (MnGa). The MM-MS_B interface with the bridge (B) connection of MnMn termination (MM) of D0- and L1-MnGa layers to MnSi termination (MS) of CMS layers is found to be most stable in the energy point of view. Also, a strong antiferromagnetic coupling and relatively higher spin polarization can be observed in the MM-MS_B interface. Further, a remarkable potential difference to derive electrons to transfer from MG layer to CMS layer appears at the interface. These theoretical results indicate that the MG/CMS bilayers are promising candidates as coupled composites, and moreover, the D0-MG/CMS bilayer is better than L1-MG/CMS bilayer due to its larger spin polarization and built-in field at the interface.
直接耦合的硬铁磁体和软铁磁体通常被用作混合电极，以提高垂直磁隧道结（pMTJ）中的隧道磁电阻（TMR）比率。在本文中，我们采用具有广义梯度近似（GGA）的密度泛函理论（DFT）来研究四方Heusler型MnGa（MG）/L2-CoMnSi（CMS）Heusler合金双层的界面结构和磁行为，其中MnGa为D0-MnGa合金（MnGa）和L1-MnGa合金（MnGa）。从能量角度来看，发现D0-和L1-MnGa层的MnMn端接（MM）与CMS层的MnSi端接（MS）通过桥接（B）连接的MM-MS_B界面最稳定。此外，在MM-MS_B界面中可以观察到强反铁磁耦合和相对较高的自旋极化。此外，在界面处出现了一个显著的电位差，促使电子从MG层转移到CMS层。这些理论结果表明，MG/CMS双层是有前途的耦合复合材料候选者，而且，D0-MG/CMS双层由于其在界面处具有更大的自旋极化和内建场，比L1-MG/CMS双层更好。
