反铁磁Cr插入层对CoFe/MgO/CoFe磁性隧道结的隧穿磁电阻的影响

Effect of antiferromagnetic Cr layer on tunneling magnetoresistance of CoFe/MgO/CoFe magnetic tunnel junction

利用基于密度泛函理论和非平衡态格林函数的第一性原理计算研究了CoFe/MgO/CoFe磁性隧道结的隧穿磁电阻效应.给出了该隧道结隧穿磁电阻与偏压的依赖关系,并计算了平行结构与反平行结构相应的I-V特性曲线和传输谱.通过在一侧电极与势垒层之间插入反铁磁金属Cr层,观察到了隧穿磁电阻、电导随插入层Cr层数增加发生衰减和2个原子层周期的振荡现象,这主要是由于Cr拥有反铁磁结构,在Cr/MgO界面形成了与Cr磁矩取向相关的界面散射.

We carried out the first-principles calculations based on density functional theory （DFT） and non-e- quilibrium Green function （NEGF） to investigate the tunneling magnetoresistance （TMR） effect in CoFe/MgO/ CoFe magnetic tunnel junctions. The TMR dependence on bias voltage was displayed and corresponding I-V curves and transmission spectra with parallel and antiparallel alighnment were also provided. By inserting antifer- romagnetic Cr layer between one electrode and the barrier, the decay and 2-layer-period oscillation phenomenon in TMR ratio were found. This effect is attributed to the interface scattering on Cr/MgO interface related to Cr magnetic orientation which is arisen by the antiferromagnetic ordering of Cr layer.