Visualizing Tailored Spin Phenomena in a Reduced‐Dimensional Topological Superlattice
Visualizing Tailored Spin Phenomena in a Reduced‐Dimensional Topological Superlattice
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可视化降维拓扑超晶格中的定制自旋现象
DOI：
10.1002/adma.202005315
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发表时间：
2020
影响因子：
29.4
通讯作者：
Cheng Zhao‐hua
中科院分区：
文献类型：
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作者：
Sun Rui;Yang Shijia;Yang Xu;Kumar A.;Vetter Eric;Xue Wenhua;Li Yan;Li Na;Li Yang;Zhang Shihao;Ge Binghui;Zhang Xiang‐qun;He Wei;Kemper Alex;er F.;Sun Dali;Cheng Zhao‐hua
紧急拓扑绝缘体（ti）及其设计在操纵和传输自旋信息以实现超低功耗自旋电子应用方面具有很高的需求。在这里，通过分子束外延控制终止，可以在单个降维TI‐超晶格（Bi2/Bi2Se3）‐（Bi2/Bi2Se3）Nor（□/Bi2Se3）‐（Bi2/Bi2Se3）N（Nis是重复单元，□代表一个空层）中实现具有定制自旋特性的不同拓扑状态。该Bi2‐端超晶格表现为单狄拉克锥，自旋动量分裂≈0.5 Å−1，产生明显的逆Edelstein效应，相干长度高达1.26 nm。相比之下，端接Bi2Se3的超晶格被确定为双重TI，受到共存的时间反转和镜像对称性的保护，显示出意想不到的长自旋寿命，高达1ns。这项工作阐明了维度和双拓扑相在选择所需自旋特性中的关键作用，为高性能TI自旋电子器件的工程拓扑超晶格提供了一条有希望的途径。
Emergent topological insulators (TIs) and their design are in high demand for manipulating and transmitting spin information toward ultralow‐power‐consumption spintronic applications. Here, distinct topological states with tailored spin properties can be achieved in a single reduced‐dimensional TI‐superlattice, (Bi2/Bi2Se3)‐(Bi2/Bi2Se3)Nor (□/Bi2Se3)‐(Bi2/Bi2Se3)N(Nis the repeating unit, □ represents an empty layer) by controlling the termination via molecular beam epitaxy. The Bi2‐terminated superlattice exhibits a single Dirac cone with a spin momentum splitting ≈0.5 Å−1, producing a pronounced inverse Edelstein effect with a coherence length up to 1.26 nm. In contrast, the Bi2Se3‐terminated superlattice is identified as a dual TI protected by coexisting time reversal and mirror symmetries, showing an unexpectedly long spin lifetime up to 1 ns. The work elucidates the key role of dimensionality and dual topological phases in selecting desired spin properties, suggesting a promise route for engineering topological superlattices for high‐performance TI‐spintronic devices.