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arXiv 2103.09934cond-mat.mes-hall
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${\text{MoS}_{2}-\text{MoSe}_{2}}$界面电子和空穴的自旋/谷耦合动力学

Spin/valley coupled dynamics of electrons and holes at the ${\text{MoS}_{2}-\text{MoSe}_{2}}$ interface

Abhijeet Kumar, Denis Yagodkin, Nele Stetzuhn, Sviatoslav Kovalchuk, Alexey Melnikov, Peter Elliott, Sangeeta Sharma, Cornelius Gahl, Kirill I. Bolotin

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15 + 6 pages; 4 + 3 figures
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摘要：

过渡金属二硫族化合物（TMD）中的自旋和谷自由度耦合被认为是一种很有前途的信息处理平台。在这里，我们使用一个TMD异质结构${\text{MoS}_{2}-\text{MoSe}_{2}}$研究跨界面的自旋/谷极化载流子的光泵浦，并阐明其随后的弛豫机制。通过应用时间分辨克尔和反射率光谱，我们发现，光激发载流子保存其自旋的两个隧穿方向的接口。在此之后，我们测量显着不同的自旋/谷退极化率的电子和空穴，$\sim 30\,{\text{ns}}^{-1}$和$< 1\,{\text{ns}}^{-1}$，分别表明，这种差异涉及到的导带和价带的TMD的自旋轨道分裂的差距。我们的工作提供了深入了解不受复杂激子过程影响的自由载流子的自旋/谷动力学，并建立了TMD异质结构作为自旋/谷电子器件中的自旋电流发生器。

英文摘要：

The coupled spin and valley degrees of freedom in transition metal dichalcogenides (TMDs) are considered a promising platform for information processing. Here, we use a TMD heterostructure ${\text{MoS}_{2}-\text{MoSe}_{2}}$ to study optical pumping of spin/valley polarized carriers across the interface and to elucidate the mechanisms governing their subsequent relaxation. By applying time-resolved Kerr and reflectivity spectroscopies, we find that the photoexcited carriers conserve their spin for both tunneling directions across the interface. Following this, we measure dramatically different spin/valley depolarization rates for electrons and holes, $\sim 30\,{\text{ns}}^{-1}$ and $< 1\,{\text{ns}}^{-1}$, respectively and show that this difference relates to the disparity in the spin-orbit splitting in conduction and valence bands of TMDs. Our work provides insights into the spin/valley dynamics of free carriers unaffected by complex excitonic processes and establishes TMD heterostructures as generators of spin currents in spin/valleytronic devices.

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