Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices.
Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices.
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DOI：
10.1038/srep45594
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发表时间：
2017-04-04
影响因子：
4.6
通讯作者：
McKenna KP
中科院分区：
文献类型：
--
作者：
Bean JJ;Saito M;Fukami S;Sato H;Ikeda S;Ohno H;Ikuhara Y;McKenna KP
多晶金属氧化物在纳米电子学、光电子学和催化等领域有着广泛的应用。虽然晶界缺陷是普遍存在的，其结构和电子性质是非常了解，因为它是非常具有挑战性的直接探测埋界面的结构。在本文中，我们结合联合收割机新的平面视图高分辨率透射电子显微镜和第一性原理计算提供原子水平的理解的结构和性质的晶界的磁性隧道结的势垒层。我们发现，高度[001]织构的MgO薄膜包含大量的倾斜晶界。第一原理计算揭示了这些晶界是如何与局部减少带隙（高达3 eV）。使用一个简单的模型，我们展示了如何分流的比例通过晶界的隧道电流施加限制的最大磁阻，可以实现在设备。
Polycrystalline metal oxides find diverse applications in areas such as nanoelectronics, photovoltaics and catalysis. Although grain boundary defects are ubiquitous their structure and electronic properties are very poorly understood since it is extremely challenging to probe the structure of buried interfaces directly. In this paper we combine novel plan-view high-resolution transmission electron microscopy and first principles calculations to provide atomic level understanding of the structure and properties of grain boundaries in the barrier layer of a magnetic tunnel junction. We show that the highly [001] textured MgO films contain numerous tilt grain boundaries. First principles calculations reveal how these grain boundaries are associated with locally reduced band gaps (by up to 3 eV). Using a simple model we show how shunting a proportion of the tunnelling current through grain boundaries imposes limits on the maximum magnetoresistance that can be achieved in devices.