A nonequilibrium Green’s function (NEGF) formulation to study the transport characteristics of magnetic tunnel junctions (MTJs) that contains impurities at the barrier region and many-body interaction at the electrode region is presented. The formulation makes use of the already developed NEGF method for MTJs without any impurities and the impurity Green’s function is obtained using Haldane’s approach that explicitly takes into account the on-site Coulomb interaction ([Formula: see text]) of the impurity. The formulation is used to obtain the spin-dependent tunnel current of model MTJs as a function of the applied bias for different values of [Formula: see text] corresponding to both the parallel and antiparallel configuration of the end electrodes of the MTJ. The tunnel currents are used to obtain the tunnel magnetoresistance (TMR) of the MTJ and we observed from our study that the TMR is strongly influenced by the impurities. The TMR is found to be reduced compared to that of the MTJ without impurities and the bias dependence of the TMR is found to be strongly influenced by [Formula: see text]. Our studies revealed that the MTJ can exhibit almost completely spin polarized current at certain values of [Formula: see text].

中文翻译：

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包含安德森杂质的磁隧道结传输特性的非平衡格林函数建模

提出了一种非平衡格林函数 (NEGF) 公式，用于研究在势垒区域包含杂质和在电极区域包含多体相互作用的磁隧道结 (MTJ) 的传输特性。该公式利用已经开发的 NEGF 方法用于 MTJ，没有任何杂质，杂质格林函数是使用 Haldane 的方法获得的，该方法明确考虑了杂质的现场库仑相互作用（[公式：见文本]）。该公式用于获得模型 MTJ 的自旋相关隧道电流，作为所施加的偏压的函数，[公式：参见文本] 的不同值对应于 MTJ 端电极的平行和反平行配置。隧道电流用于获得 MTJ 的隧道磁阻 (TMR)，我们从研究中观察到，TMR 受到杂质的强烈影响。与没有杂质的 MTJ 相比，发现 TMR 降低了，并且发现 TMR 的偏置依赖性受到[公式：见正文]的强烈影响。我们的研究表明，在 [公式：见正文] 的某些值下，MTJ 可以表现出几乎完全自旋极化电流。