隧道磁电阻效应中的两种不同的理论方法

Two different approaches in the magnetic tunneling junctions

使用两种不同的理论方法来计算磁性隧道结中的隧道磁电阻 .结果显示 ,Slonczewski模型得出的隧道磁电阻比Julliere公式得到的要大得多 .在Slonczewski模型中 ,当两边铁磁体的磁化方向相反时 ,为了确保平行于界面方向上的动量守恒 ,费米面上的电子只有一部分参与了隧穿过程 ;而在隧道哈密顿方法中 ,则假设费米面上所有的电子都参与了 .还发现 ,在Slonczewski模型中 。

In this paper we use two different approaches to calculating the tunneling magnetoresistance (TMR) in magnetic tunnel junctions.It is found that the result for TMR calculated from the Slonczewski model is always greater than that of from the Julliere formula.In the Slonczewski model only a part of electrodes at the Fermi level participate in the tunneling process with the momentum parallel to the interface conservating if the magnetizations of two ferromagnetic electrodes are antiparallel to each other;while in the tunneling Hamiltonian approach all the electrodes at the Fermi level are assumed to participate in the tunneling process. Beside,there is only small difference between the magnitude of TMR calculated by using the δ \|type barrier and the rec tangular one in the Slonczewski model.