We theoretically demonstrate a Dirac fermion metagrating which is an artificially engineered material in graphene. Although its physics mechanism is different from that of optical metagrating, both of them can deliver waves to one desired diffraction order. Here we design the metagrating as a linear array of bias-tunable quantum dots to engineer electron beams to travel along the -1st-order transmission direction with unity efficiency. Equivalently, electron waves are deflected by an arbitrary large-angle ranging from 90° to 180° by controlling the bias. The propagation direction changes abruptly without the necessity of a large transition distance. This effect is irrelevant to complete band gaps and thus the advantages of graphene with high mobility are not destroyed. This can be attributed to the whispering-gallery modes, which evolve with the angle of incidence to completely suppress the other diffraction orders supported by the metagrating and produce unity-efficiency beam deflection by enhancing the -1st transmitted diffraction order. The concept of Dirac fermion metagratings opens up a new paradigm in electron beam steering and could be applied to achieve two-dimensional electronic holography.

我们从理论上证明了狄拉克费米子转移是一种石墨烯中的人工工程材料。尽管它的物理机制与光学迁移的机制不同，但它们都可以将波传递到一个所需的衍射级。在这里，我们将迁移设计为偏置可调量子点的线性阵列，以工程化电子束以统一效率沿着-1阶传输方向传播。等效地，通过控制偏压，电子波以90°至180°范围内的任意大角度偏转。传播方向突然改变而无需大的过渡距离。该效果与完整的带隙无关，因此不会破坏具有高迁移率的石墨烯的优点。这可以归因于耳语画廊模式，它们随着入射角的变化而完全抑制了由迁移所支撑的其他衍射级，并通过提高-1st透射衍射级来产生单位效率的光束偏转。狄拉克费米子迁移的概念为电子束转向开辟了新的范式，可用于实现二维电子全息。