Effects of Randomness on Tunnel Conductance and Magnetoresistance in Ferromagnetic Tunnel Junctions
Effects of Randomness on Tunnel Conductance and Magnetoresistance in Ferromagnetic Tunnel Junctions
复制标题
随机性对铁磁隧道结隧道电导和磁阻的影响
DOI：
10.1143/jpsj.68.1632
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发表时间：
1999
影响因子：
1.7
通讯作者：
S. Maekawa
中科院分区：
文献类型：
--
作者：
H. Itoh;A. Shibata;Takao Kumazaki;J. Inoue;S. Maekawa
从理论上研究了随机性对铁磁隧道结的隧道电导和隧道磁电阻效应的影响。重点讨论了界面随机性和金属引线电子结构的综合影响。在单轨道紧束缚模型中，利用Kubo公式和相干势近似，在T =0 K和零偏压极限下，考虑了无规性，得到了电导的表达式.计算了电导的顶点修正，使之满足电流守恒定律。隧道电导和隧道磁电阻与随机性和无随机性被发现依赖于费米能量EF和费米面的形状。TMR受随机性的影响，当EF接近带底时，TMR会增加，而当EF较高时，TMR会降低。计算了TMR随势垒高度和厚度的变化。
The effects of randomness on the tunnel conductance and the tunnel magnetoresistance (TMR) are studied theoretically for ferromagnetic tunnel junctions. An emphasis is put on a combined effects of the interfacial randomness and the electronic structures of the metallic leads. The conductance is formulated by taking the randomness into account at T =0 K and zero bias limit by using the Kubo formula and the coherent potential approximation in a single orbital tight-binding model. The vertex correction to the conductance is calculated so as to satisfy the current conservation law. The tunnel conductance and the TMR with and without randomness are found to depend on the Fermi energy E F and the shape of the Fermi surface. The TMR is affected by the randomness in such a way that it can be increased by the randomness when E F is close to the band bottom, while it is decreased when E F is higher. The variation of the TMR with the barrier height and thickness is also calculated.