Two-dimensional materials offer new opportunities for both fundamental science and technological applications, by exploiting the electron’s spin. Although graphene is very promising for spin communication due to its extraordinary electron mobility, the lack of a bandgap restricts its prospects for semiconducting spin devices such as spin diodes and bipolar spin transistors. The recent emergence of two-dimensional semiconductors could help overcome this basic challenge. In this letter we report an important step towards making two-dimensional semiconductor spin devices. We have fabricated a spin valve based on ultrathin (~5 nm) semiconducting black phosphorus (bP), and established fundamental spin properties of this spin channel material, which supports all electrical spin injection, transport, precession and detection up to room temperature. In the non-local spin valve geometry we measure Hanle spin precession and observe spin relaxation times as high as 4 ns, with spin relaxation lengths exceeding 6 μm. Our experimental results are in a very good agreement with first-principles calculations and demonstrate that the Elliott–Yafet spin relaxation mechanism is dominant. We also show that spin transport in ultrathin bP depends strongly on the charge carrier concentration, and can be manipulated by the electric field effect.

中文翻译：

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具有纳秒级旋转寿命的门可调黑磷旋转阀

二维材料通过利用电子的自旋，为基础科学和技术应用提供了新的机遇。尽管石墨烯因其非凡的电子迁移率而非常有希望用于自旋通信，但缺乏带隙限制了其在半导体自旋器件（如自旋二极管和双极自旋晶体管）中的应用前景。二维半导体的最新出现可以帮助克服这一基本挑战。在这封信中，我们报告了朝着制造二维半导体自旋器件迈出的重要一步。我们制造了一种基于超薄（〜5 nm）半导体黑磷（bP），并建立了这种自旋通道材料的基本自旋特性，可支持所有电自旋注入，传输，进动和检测，直至室温。在非局部自旋阀几何形状中，我们测量了Hanle自旋进动，并观察了高达4 ns的自旋弛豫时间，自旋弛豫长度超过 6μm。我们的实验结果与第一性原理的计算非常吻合，并证明了Elliott-Yafet自旋弛豫机制是主要的。我们还表明，超薄bP中的自旋运输在很大程度上取决于电荷载流子浓度，并且可以通过电场效应来操纵。