Generation, transport and detection of valley-locked spin photocurrent in WSe2-graphene-Bi2Se3 heterostructures
Generation, transport and detection of valley-locked spin photocurrent in WSe2-graphene-Bi2Se3 heterostructures
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DOI：
10.1038/s41565-018-0195-y
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发表时间：
2018-10-01
影响因子：
38.3
通讯作者：
Choi, Hyunyong
中科院分区：
文献类型：
--
作者：
Cha, Soonyoung;Noh, Minji;Choi, Hyunyong
能够将目标自由度 (DoF) 与其他自由度隔离的量子光电器件在现代信息技术中实现了新的应用。许多固态自旋电子学工作都集中在将自旋 DoF 与电荷 DoF(1) 分离的方法上，但许多相关问题仍未解决。尽管最近出现的原子薄过渡金属二硫化物 (TMD) 已经能够使用谷赝自旋作为替代 DoF(2,3)，但将自旋 DoF 与谷 DoF 分开并非易事，因为时间反转谷 DoF 本质上与自旋 DoF(4) 锁定。在这里，我们展示了横向 TMD-石墨烯拓扑绝缘体异质器件，具有这种 DoF 选择性测量的可能性。我们通过双电层 WSe2 晶体管中的圆形光电效应产生谷锁定自旋 DoF。然后，锁谷自旋光载流子在亚微米长的石墨烯层中扩散，并使用特征自旋动量锁定通过非局部电检测在拓扑绝缘体中单独测量自旋自由度。我们的集成器件在室温下运行，表现出高于 0.5 的非局部自旋极化度，为独立利用谷和自旋自由度的耦合光自旋谷电子应用提供了潜力。
Quantum optoelectronic devices capable of isolating a target degree of freedom (DoF) from other DoFs have allowed for new applications in modern information technology. Many works on solid-state spintronics have focused on methods to disentangle the spin DoF from the charge DoF(1), yet many related issues remain unresolved. Although the recent advent of atomically thin transition metal dichalcogenides (TMDs) has enabled the use of valley pseudospin as an alternative DoF(2,3), it is nontrivial to separate the spin DoF from the valley DoF since the time-reversal valley DoF is intrinsically locked with the spin DoF(4). Here, we demonstrate lateral TMD-graphene-topological insulator hetero-devices with the possibility of such a DoF-selective measurement. We generate the valley-locked spin DoF via a circular photogalvanic effect in an electric-double-layer WSe2 transistor. The valley-locked spin photocarriers then diffuse in a submicrometre-long graphene layer, and the spin DoF is measured separately in the topological insulator via non-local electrical detection using the characteristic spin-momentum locking. Operating at room temperature, our integrated devices exhibit a non-local spin polarization degree of higher than 0.5, providing the potential for coupled opto-spin-valleytronic applications that independently exploit the valley and spin DoFs.