Coherent Resonant Tunneling through Double Metallic Quantum Well States
Coherent Resonant Tunneling through Double Metallic Quantum Well States
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通过双金属量子阱态的相干谐振隧道
DOI：
10.1021/acs.nanolett.9b00205
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发表时间：
2019
期刊：
影响因子：
10.8
通讯作者：
Lu Yuan
中科院分区：
文献类型：
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作者：
Tao Bingshan;Wan Caihua;Tang Ping;Feng Jiafeng;Wei Hongxiang;Wang Xiao;Andrieu Stephane;Yang Hongxin;Chshiev Mairbek;Devaux Xavier;Hauet Thomas;Montaigne Francois;Mangin Stephane;Hehn Michel;Lacour Daniel;Han Xiufeng;Lu Yuan
多金属量子阱结构的共振隧穿研究不仅对量子输运的基本认识具有重要意义，而且对产生先进功能的自旋电子器件具有巨大的潜力。然而，由于金属量子阱系统的电子相位相干长度较短，因此设计这样的结构仍然具有挑战性。在这里，我们展示了双量子阱结构的成功制造在一个单一的完全外延磁性隧道结（MTJ）异质结构，其中两个铁量子阱层夹在三个MgAlOx隧道势垒。我们给出了在两个量子阱中通过离散量子阱态的相干共振隧穿的明显证据。只有当两个量子阱之间的中间势垒足够薄，并且在一定的偏压下两个量子阱中同时存在可用的量子阱态时，相干共振隧穿条件才能满足。与单量子阱结构相比，双量子阱MTJ的共振隧穿效应增强了能量过滤效应，产生了较强的电导振荡，且峰值宽度较窄（约为单量子阱结构的一半）。这项研究提出了一个全面的理解，在MTJ与多个量子阱，这是必不可少的未来发展的新的自旋电子器件在量子隧穿制度的共振隧穿机制。
Study of resonant tunneling through multimetallic quantum well (QW) structure is not only important for the fundamental understanding of quantum transport but also for the great potential to generate advanced functionalities of spintronic devices. However, it remains challenging to engineer such a structure due to the short electron phase coherence length in metallic QW system. Here, we demonstrate the successful fabrication of double-QW structure in a single fully epitaxial magnetic tunnel junction (MTJ) heterostructure, where two Fe QW layers are sandwiched between three MgAlOxtunnel barriers. We show clear evidence of the coherent resonant tunneling through the discrete QW states in the two QWs. The coherent resonant tunneling condition is fulfilled only when the middle barrier between the two QWs is thin enough and available QW states are present simultaneously in both QWs under a certain bias. Compared to the single QW structure, the resonant tunneling in double-QW MTJ produces strong conductivity oscillations with much narrower peak width (about half) owing to the enhanced energy filtering effect. This study presents a comprehensive understanding of the resonant tunneling mechanism in MTJ with multiple QWs, which is essential for future development of new spintronic devices operating in the quantum tunneling regime.