Mono- (or few) layer black phosphorus (BP) is highly expected to be a next-generation two-dimensional (2D) atom-thin semiconductor. Compared with other 2D atom-thin layers, BP has a significantly anisotropic atomic structure, which can provide unique electronic, optical, and magnetic properties. Herein, we report the observation of B2/3 magnetic-field (B) dependence of the Hall resistance with extremely small quantized levels in the low-B regime of the few-layer BP, which are associated with the anisotropic electronic structure confirmed by largely anisotropic hole mobilities. One of the qualitative interpretations for the B2/3 dependence is the possible presence of a uniaxial Dirac spectrum (arising from a closed band gap caused by uniaxial stretch along the buckling armchair direction, which is occasionally introduced by a process for cutting and wire-bonding samples, confirmed by Raman spectroscopy) and its hybridization with a Schr?dinger spectrum existing along a zigzag direction. The observed phenomena imply significant potential due to strong anisotropy of atom-thin (few-layer) BP, which is highly expected to open doors to novel physics and its application for innovative 2D atom-thin devices.
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机译：单层（或很少层）黑磷（BP）有望成为下一代二维（2D）原子薄半导体。与其他2D原子薄层相比，BP具有明显的各向异性原子结构，可以提供独特的电子，光学和磁性特性。在此，我们报告了霍尔电阻对 B 2/3 磁场（ B ）的依赖性的观察结果在几层BP的低 B 态中具有极小的量化水平，这与各向异性空穴迁移率得到很大证实的各向异性电子结构有关。对 B 2/3 依赖性的定性解释之一是可能存在单轴Dirac谱（由封闭带隙引起通过沿屈曲扶手椅方向的单轴拉伸，有时是通过切割和键合样品的工艺引入的，拉曼光谱法证实了这一点），并与之字形存在的薛定er光谱杂交。由于原子薄（几层）BP的强各向异性，观察到的现象暗示了巨大的潜力，人们高度期望这为新型物理学及其在创新的2D原子薄设备中的应用打开了大门。
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