Feng Yu, Cheng Zhenxiang, Wang Xiaotian
Laboratory for Quantum Design of Functional Materials, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, China.
Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, Australia.
Front Chem. 2019 Aug 27;7:550. doi: 10.3389/fchem.2019.00550. eCollection 2019.
Equiatomic quaternary Heusler compounds (EQHCs) generally have the advantages of high Curie temperature, large spin polarization and long spin diffusion length, and they are regarded as one of the most promising candidates for spintronics devices. Herein, we report a theoretical investigation on an EQHC CoRhMnGe based magnetic tunnel junction (MTJ) with (i) MnGe-terminated interface and (ii) modified pure Mn terminated interface, i.e., MnMn-terminated interface. By employing first principle calculations combined with non-equilibrium Green's function, the local density of states (LDOS), transmission coefficient, spin-polarized current, tunnel magnetoresistance (TMR) ratio and spin injection efficiency (SIE) as a function of bias voltage are studied. It reveals that when the MTJ under equilibrium state, TMR ratio of MnGe-terminated structure is as high as 3,438%. When the MTJ is modified to MnMn-terminated interface, TMR ratio at equilibrium is enhanced to 2 × 10%, and spin filtering effects are also strengthened. When bias voltage is applied to the MTJ, the TMR ratio of the MnGe-terminated structure suffers a dramatic loss. While the modified MnMn-terminated structure could preserve a large TMR value of 1 × 10%, even bias voltage rises up to 0.1 V, showing a robust bias endurance. These excellent spin transport properties make the CoRhMnGe a promising candidate material for spintronics devices.
等原子四元赫斯勒化合物（EQHCs）通常具有居里温度高、自旋极化率大以及自旋扩散长度长等优点，它们被认为是自旋电子器件最有前途的候选材料之一。在此，我们报道了对一种基于EQHC CoRhMnGe的磁性隧道结（MTJ）的理论研究，该MTJ具有（i）MnGe终止界面和（ii）改性的纯Mn终止界面，即MnMn终止界面。通过采用第一性原理计算结合非平衡格林函数，研究了作为偏置电压函数的局域态密度（LDOS）、透射系数、自旋极化电流、隧道磁电阻（TMR）比和自旋注入效率（SIE）。结果表明，当MTJ处于平衡状态时，MnGe终止结构的TMR比高达3438%。当MTJ改性为MnMn终止界面时，平衡时的TMR比提高到2×10%，自旋过滤效应也得到增强。当向MTJ施加偏置电压时，MnGe终止结构的TMR比急剧下降。而改性的MnMn终止结构即使在偏置电压升至0.1 V时仍能保持1×10%的大TMR值，显示出强大的偏置耐受性。这些优异的自旋输运特性使CoRhMnGe成为自旋电子器件有前途的候选材料。
