強磁性トンネル接合における絶縁障壁と磁気抵抗 (<特集>多層膜・人工格子・グラニューラー)

概要

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The dependence of the tunneling magnetoresistive effect on the barrier height was investigated. The magnitude of the barrier height increased with increasing aluminum oxidation temperature and time from 0.3 to 2.3 eV in Fe/Al oxide/Fe junctions. However, those values are smaller than those reported for an Al_2PO_3 barrier. A possible reason for this is that the barrier is not pure Al_2O_3, but AlO_x, or another oxide created by interface mixing between Fe and Al oxide. On the other hand, the magnetoresistance ratio in these junctions varied up to 18% at room temperature and up to 30% at 4.2 K. The dependence of the magnetoresistance ratio at 4.2 K on the barrier height is roughly the same as predicted by Slonczewski's theory. This result shows that the effective spin polarization of ferromagnetic electrodes changes according to the barrier height.
社団法人日本磁気学会の論文
1997-04-15