Kalameitsev A V, Kovalev V M, Savenko I G
Rzhanov Institute of Semiconductor Physics SB RAS, 630090 Novosibirsk, Russia.
Novosibirsk State Technical University, Novosibirsk, 630072 Russia.
Phys Rev Lett. 2019 Jun 28;122(25):256801. doi: 10.1103/PhysRevLett.122.256801.
We report on the novel valley acoustoelectric effect, which can arise in a 2D material, like a transition metal dichalcogenide monolayer, residing on a piezoelectric substrate. The essence of this effect lies in the emergence of a drag electric current (and a spin current) due to a propagating surface acoustic wave. This current consists of three contributions, one independent of the valley index and proportional to the acoustic wave vector, the other arising due to the trigonal warping of the electron dispersion, and the third one is due to the Berry phase, which Bloch electrons acquire traveling along the crystal. As a result, there appear components of the current orthogonal to the acoustic wave vector. Further, we build an angular pattern, encompassing nontrivial topological properties of the acoustoelectric current, and suggest a way to run and measure the conventional diffusive, warping, and acoustoelectric valley Hall currents independently. We develop a theory, which opens a way to manipulate valley transport by acoustic methods, expanding the applicability of valleytronic effects on acoustoelectronic devices.
我们报道了一种新型的谷声电效应，这种效应可能出现在二维材料中，比如位于压电衬底上的过渡金属二硫族化合物单层。这种效应的本质在于，由于传播的表面声波而出现的拖曳电流（以及自旋电流）。该电流由三部分组成，一部分与谷指数无关且与声波矢量成正比，另一部分是由于电子色散的三角翘曲产生的，第三部分则是由于布洛赫电子沿晶体传播时获得的贝里相位。结果，出现了与声波矢量正交的电流分量。此外，我们构建了一个包含声电电流非平凡拓扑性质的角向图案，并提出了一种独立运行和测量传统扩散、翘曲和声电谷霍尔电流的方法。我们发展了一种理论，该理论为通过声学方法操纵谷输运开辟了道路，扩展了谷电子学效应在声电器件中的适用性。
