论文标题
亚稳态BCC Coxmn100-X（001）铁磁层的晶格软化
Lattice Softening in Metastable bcc CoxMn100-x(001) Ferromagnetic Layers for a Strain-Less Magnetic Tunnel Junction
论文作者
论文摘要
在Spintronics中，长期存在的问题之一是为什么基于MGO的磁性隧道连接点（MTJ）几乎是在室温（RT）上实现大型隧道磁力（TMR）比的唯一选择，但不如理论预测那么大。这项研究的重点是使用亚稳态BCC Coxmn100-X铁磁膜的几乎无应变MTJ的发展。我们已经研究了由COXMN100-X/MGO/COXMN100-X（X = 66、75、83和86）组成的MTJ的结晶程度。横截面高分辨率透射电子显微镜（HRTEM）表明，这些层的几乎一致的晶格常数为66 <x <83，在RT处将大的TMR比保持229％，证实了MGO/CO75MN25 Interface的Coxmn100-X层的柔软性质。另一方面，对于X = 86，发现TMR比在RT时降低至142％，这部分归因于MGO/CO86MN14接口的位错数增加，而Mgo屏障中鉴定出的无定形晶粒。 Ab-Initio计算证实了COMN中广泛组成范围的晶体变形稳定性，证明了无应变界面的优势对于更大的TMR比率。
In spintronics, one of the long standing questions is why the MgO-based magnetic tunnel junction (MTJ) is almost the only option to achieve a large tunnelling magnetoresistance (TMR) ratio at room temperature (RT) but not as large as the theoretical prediction. This study focuses on the development of an almost strain-free MTJ using metastable bcc CoxMn100-x ferromagnetic films. We have investigated the degree of crystallisation in MTJ consisting of CoxMn100-x/MgO/CoxMn100-x (x = 66, 75, 83 and 86) in relation to their TMR ratios. Cross-sectional high resolution transmission electron microscopy (HRTEM) reveals that almost consistent lattice constants of these layers for 66 < x < 83 with maintaining large TMR ratios of 229% at RT, confirming the soft nature of the CoxMn100-x layer with some dislocations at the MgO/Co75Mn25 interfaces. For x = 86, on the other hand, the TMR ratio is found to be reduced to 142% at RT, which is partially attributed to the increased number of the dislocations at the MgO/Co86Mn14 interfaces and amorphous grains identified in the MgO barrier. Ab-initio calculations confirm the crystalline deformation stability across a broad compositional range in CoMn, proving the advantage of a strain-free interface for much larger TMR ratios.
