Tunneling of electrons in conventional and half-metallic systems: Towards very large magnetoresistance
Tunneling of electrons in conventional and half-metallic systems: Towards very large magnetoresistance
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DOI：
10.1103/physrevb.56.2344
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发表时间：
1997-08
影响因子：
3.7
通讯作者：
A. Bratkovsky
中科院分区：
文献类型：
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作者：
A. Bratkovsky
分析了铁磁-绝缘体-铁磁结（包括半金属系统）的隧道磁电阻效应。在修正的标准模型中的直接隧穿进行了比较，杂质辅助和共振TMR。铁族系统中的直接隧穿导致电阻的约20%的变化，如实验所观察到的。杂质辅助隧穿使铁基电极的TMR降低到4%，并且来自缺陷态的自旋翻转散射将进一步降低该值。共振隧穿二极管结构将给出约8%的TMR。该模型适用于定性的半金属与100%的自旋极化，在没有自旋翻转的情况下，电阻的变化可能是任意大。即使在不完美的磁性配置的情况下，电阻变化也可以是几个1000%。半金属系统的例子是CrO 2/TiO 2和CrO 2/RuO 2，并简要介绍了它们的特殊能带结构。
The tunnel magnetoresistance (TMR) is analyzed for ferromagnet-insulator-ferromagnet junctions, including half-metallic systems. Direct tunneling in a corrected standard model is compared with impurity-assisted and resonant TMR. Direct tunneling in iron group systems leads to about a 20% change in resistance, as observed experimentally. Impurity-assisted tunneling decreases the TMR down to 4% with Fe-based electrodes, and spin-flip scattering from defect states will further reduce this value. A resonant tunneling diode structure would give a TMR of about 8%. The model applies qualitatively to half-metallics with 100% spin polarization, where the change in resistance in the absence of spin-flips may be arbitrarily large. Even in the case of imperfect magnetic configurations the resistance change can be a few 1000 percent. Examples of half-metallic systems are CrO 2/TiO 2 and CrO 2/RuO 2, and a brief account of their peculiar band structures is presented.