Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
Nat Commun. 2018 Apr 13;9(1):1455. doi: 10.1038/s41467-018-03897-3.
The field of valleytronics has promised greater control of electronic and spintronic systems with an additional valley degree of freedom. However, conventional and two-dimensional valleytronic systems pose practical challenges in the utilization of this valley degree of freedom. Here we show experimental evidences of the valley effect in a bulk, ambient, and bias-free model system of Tin(II) sulfide. We elucidate the direct access and identification of different sets of valleys, based primarily on the selectivity in absorption and emission of linearly polarized light by optical reflection/transmission and photoluminescence measurements, and demonstrate strong optical dichroic anisotropy of up to 600% and nominal polarization degrees of up to 96% for the two valleys with band-gap values 1.28 and 1.48 eV, respectively; the ease of valley selection further manifested in their non-degenerate nature. Such discovery enables a new platform for better access and control of valley polarization.
谷电子学领域有望通过增加谷自由度来实现对电子和自旋电子系统的更好控制。然而，传统的二维谷电子学系统在利用这个谷自由度方面存在实际挑战。在这里，我们在二硫化锡的体、环境和无偏压模型系统中展示了谷效应的实验证据。我们根据光反射/透射和光致发光测量中线性偏振光吸收和发射的选择性，阐明了对不同谷集的直接访问和识别，并分别演示了具有 1.28 和 1.48 eV 带隙值的两个谷的高达 600%的强光学二色各向异性和高达 96%的标称偏振度；谷选择的容易程度进一步体现在它们的非简并性质上。这种发现为更好地访问和控制谷极化提供了一个新的平台。
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