Xiang Z J, Ye G J, Shang C, Lei B, Wang N Z, Yang K S, Liu D Y, Meng F B, Luo X G, Zou L J, Sun Z, Zhang Y, Chen X H
Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Key Laboratory of Strongly-coupled Quantum Matter Physics, Chinese Academy of Sciences, Hefei, Anhui 230026, China.
Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
Phys Rev Lett. 2015 Oct 30;115(18):186403. doi: 10.1103/PhysRevLett.115.186403. Epub 2015 Oct 28.
In a semimetal, both electrons and holes contribute to the density of states at the Fermi level. The small band overlaps and multiband effects engender novel electronic properties. We show that a moderate hydrostatic pressure effectively suppresses the band gap in the elemental semiconductor black phosphorus. An electronic topological transition takes place at approximately 1.2 GPa, above which black phosphorus evolves into a semimetal state that is characterized by a colossal positive magnetoresistance and a nonlinear field dependence of Hall resistivity. The Shubnikov-de Haas oscillations detected in magnetic field reveal the complex Fermi surface topology of the semimetallic phase. In particular, we find a nontrivial Berry phase in one Fermi surface that emerges in the semimetal state, as evidence of a Dirac-like dispersion. The observed semimetallic behavior greatly enriches the material property of black phosphorus and sets the stage for the exploration of novel electronic states in this material.
在半金属中，电子和空穴都对费米能级处的态密度有贡献。小的能带重叠和多带效应产生了新颖的电子特性。我们表明，适度的静水压力有效地抑制了元素半导体黑磷中的带隙。在约1.2吉帕斯卡时发生电子拓扑转变，在此压力以上，黑磷演变成一种半金属态，其特征是具有巨大的正磁阻和霍尔电阻率的非线性场依赖性。在磁场中检测到的舒布尼科夫 - 德哈斯振荡揭示了半金属相复杂的费米面拓扑结构。特别地，我们在半金属态出现的一个费米面上发现了一个非平凡的贝里相位，这是类狄拉克色散的证据。观察到的半金属行为极大地丰富了黑磷的材料特性，并为探索该材料中的新型电子态奠定了基础。
