Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering
Enhancement of spin-to-charge conversion efficiency in topological insulators by interface engineering
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DOI：
10.1063/5.0049044
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发表时间：
2021-07-01
期刊：
影响因子：
6.1
通讯作者：
Wang, Kang L.
中科院分区：
文献类型：
--
作者：
He, Haoran;Tai, Lixuan;Wang, Kang L.
基于拓扑绝缘体（TI）的异质结构由于其独特的表面状态而成为超高自旋-电荷转换效率的潜在候选材料。我们通过自旋泵测量研究了（Bi,Sb）(2)Te-3 (BST)/CoFeB、BST/Ru/CoFeB和BST/Ti/CoFeB中自旋到电荷的转换。我们发现逆Edelstein效应长度（lambda(IEE)）在Ru插入时增加了60%，而在Ti插入时保持不变。这可能是由于Ru的高电负性对BST表面态的保护。当Ru厚度大于0.5 nm时，这种增强与插入层厚度无关，这表明lambda（IEE）对TI界面非常敏感。此外，在BST/CoFeB样品中观察到一个有效的垂直磁各向异性场和额外的磁阻尼，这是由于BST和CoFeB之间的界面自旋轨道耦合。我们的工作提供了一种增强lambda（IEE）的方法，并有助于理解基于ti的系统中的电荷-自旋转换。
Topological insulator (TI) based heterostructure is a prospective candidate for ultrahigh spin-to-charge conversion efficiency due to its unique surface states. We investigate the spin-to-charge conversion in (Bi,Sb)(2)Te-3 (BST)/CoFeB, BST/Ru/CoFeB, and BST/Ti/CoFeB by spin pumping measurement. We find that the inverse Edelstein effect length (lambda(IEE)) increases by 60% with a Ru insertion while remains constant with a Ti insertion. This can be potentially explained by the protection of BST surface states due to the high electronegativity of Ru. Such enhancement is independent of the insertion layer thickness once the thickness of Ru is larger than 0.5 nm, and this result suggests that lambda(IEE) is very sensitive to the TI interface. In addition, an effectively perpendicular magnetic anisotropy field and additional magnetic damping are observed in the BST/CoFeB sample, which comes from the interfacial spin-orbit coupling between the BST and the CoFeB. Our work provides a method to enhance lambda(IEE) and is useful for the understanding of charge-to-spin conversion in TI-based systems.