Significant magnetoresistance enhancement due to a cotunneling process in a double tunnel junction with single discontinuous ferromagnetic layer insertion.
Significant magnetoresistance enhancement due to a cotunneling process in a double tunnel junction with single discontinuous ferromagnetic layer insertion.
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DOI：
10.1103/physrevlett.94.068304
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发表时间：
2005-02
影响因子：
8.6
通讯作者：
H. Sukegawa;S. Nakamura;A. Hirohata;N. Tezuka;K. Inomata
中科院分区：
文献类型：
--
作者：
H. Sukegawa;S. Nakamura;A. Hirohata;N. Tezuka;K. Inomata
我们制备了CoFe/AlOx/CoFe/AlOx/CoFe铁磁双隧道结，观察到了自旋相关的隧穿现象。通过二维地形成CoFe颗粒，中间CoFe层变得不连续，从横截面透射电子显微镜图像评估其平均直径为2.0- 4.5nm。低于50 K，库仑间隙观察到的电流-电压曲线，和磁阻比和电阻被发现显着增加，随着温度的降低。这表明在差距内共隧穿过程占主导地位，这与理论预测非常一致[Phys. Rev. Lett. 80，1758（1998）]。
We fabricate CoFe/AlOx/CoFe/AlOx/CoFe ferromagnetic double tunnel junctions and observe spin-dependent tunneling phenomena. A middle CoFe layer becomes discontinuous by forming CoFe particles two dimensionally, of which the average diameter is evaluated to be 2.0-4.5 nm from cross-sectional transmission electron microscopy images. Below 50 K, a Coulomb gap is observed in current-voltage curves, and both magnetoresistance ratios and resistances are found to increase significantly with decreasing temperature. This indicates that a cotunneling process is dominant within the gap, which agrees very well with theoretical prediction [Phys. Rev. Lett. 80, 1758 (1998)].