【摘要】 通过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/Cu/MgAl2O4(001)/CoFe磁性隧道结(MTJ)的隧穿磁电阻(TMR)效应。结果显示,在一个完整的MgAl2O4(001)晶胞上再添加三层绝缘势垒层不仅会得到更大的隧穿磁电阻,且可以得到一个相对较大的半峰值偏压Vhalf。通过在势垒层和电极之间插入非磁性材料Cu,引起隧穿磁电阻发生反转和振荡现象,分别用左端CoFe-Cu电极的态密度(DOS)和电子的自旋传输对这两种现象进行了讨论。前者主要是由于CoFe-Cu电极的态密度随Cu层的增加发生了变化,后者主要是因为隧穿电子在Cu层中形成量子阱态,发生多重散射引起的。更多还原

【Abstract】 Through the first-principle calculations based on the density functional theory and nonequilibrium Green function method,the tunneling magnetoresistance(TMR)effect in CoFe/Cu/MgAl2O4(001)/CoFe magnetic tunnel junction(MTJ)was investigated.The results indicate that by adding another three barrier layers on the whole MgAl2O4(001)unit cell,the greater TMR and a relatively large half peak bias voltage Vhalfcan be obtained.Through the insertion of a nonmagnetic Cu layer between the barrier layer and the electrode,the inverse and oscillation of the TMR were produced.The two phenomena were discussed in terms of the density of state(DOS)of the left CoFe-Cu electrode and the electron spin transport,respectively.The former is attributed to the change of the DOS of left CoFe-Cu electrode with the increase of the Cu layer number,and the latter is mainly because the tunneling electron forms the quantum well states in the Cu layer and the multiple scattering occurs.更多还原