Layer-dependent optically induced spin polarization in InSe
Layer-dependent optically induced spin polarization in InSe
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DOI：
10.1103/physrevb.107.115304
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发表时间：
2022-12
影响因子：
3.7
通讯作者：
J. Nelson;T. Stanev;Dmitry Lebedev;Trevor LaMountain;J. Gish;Hongfei Zeng;Hyeondeok Shin;O. Heinonen-O
中科院分区：
文献类型：
--
作者：
J. Nelson;T. Stanev;Dmitry Lebedev;Trevor LaMountain;J. Gish;Hongfei Zeng;Hyeondeok Shin;O. Heinonen-O
半导体中自旋的光学控制已经率先使用III-V和II-VI半导体的纳米结构，但是二维货车德瓦尔斯材料的出现为自旋电子现象提供了替代的低维平台。硒化铟（InSe）是一种III族单硫族化合物货车德瓦耳斯材料，由于其高电子迁移率、可调直接带隙和量子输运特性，在光电子学领域显示出了广阔的应用前景。有自旋相关的光学选择规则的预测表明在二维层状材料的自旋的全光激发和控制的潜力。尽管有这些预测，层相关的光学自旋现象在InSe尚未被探索。在这里，我们提出了测量层依赖的光学自旋动力学在几层和散装的InSe。偏振光致发光揭示了自旋的层依赖性光学取向，从而证明了在少层InSe的光学选择规则。自旋动力学也研究了多层InSe使用时间分辨克尔旋转光谱。通过施加平面外和平面内的静态磁场的偏振发射测量和克尔测量，分别提取的$g$因子的InSe。进一步的调查是通过使用$\textbf{k} \cdot \textbf{p}$模型，这是支持\textit{ab-initio}密度泛函理论计算进动值。预测的进动率与实验测量的比较突出了激子效应的重要性，在硒铟理解自旋动力学。自旋的光学取向是光-自旋电子学现象和器件的重要先决条件，并且InSe中自旋的层依赖性光学激发的这些首次演示为将层依赖性自旋性质与在这种材料中发现的有利的电子性质相结合奠定了基础。
Optical control of spin in semiconductors has been pioneered using nanostructures of III-V and II-VI semiconductors, but the emergence of two-dimensional van der Waals materials offers an alternative low-dimensional platform for spintronic phenomena. Indium selenide (InSe), a group-III monochalcogenide van der Waals material, has shown promise for opto-electronics due to its high electron mobility, tunable direct bandgap, and quantum transport. There are predictions of spin-dependent optical selection rules suggesting potential for all-optical excitation and control of spin in a two-dimensional layered material. Despite these predictions, layer-dependent optical spin phenomena in InSe have yet to be explored. Here, we present measurements of layer-dependent optical spin dynamics in few-layer and bulk InSe. Polarized photoluminescence reveals layer-dependent optical orientation of spin, thereby demonstrating the optical selection rules in few-layer InSe. Spin dynamics are also studied in many-layer InSe using time-resolved Kerr rotation spectroscopy. By applying out-of-plane and in-plane static magnetic fields for polarized emission measurements and Kerr measurements, respectively, the $g$-factor for InSe was extracted. Further investigations are done by calculating precession values using a $\textbf{k} \cdot \textbf{p}$ model, which is supported by \textit{ab-initio} density functional theory. Comparison of predicted precession rates with experimental measurements highlights the importance of excitonic effects in InSe for understanding spin dynamics. Optical orientation of spin is an important prerequisite for opto-spintronic phenomena and devices, and these first demonstrations of layer-dependent optical excitation of spins in InSe lay the foundation for combining layer-dependent spin properties with advantageous electronic properties found in this material.