第二类狄拉克半金属PtTe $_2$的电磁性质
Galvanomagnetic properties of the putative type-II Dirac semimetal PtTe$_2$
摘要：
铂二碲化最近被其特征在于，基于角分辨光电子能谱数据和电子能带结构计算，作为一个可能的代表II型狄拉克半金属。在这里，我们报告的磁输运行为（电阻率，霍尔效应）在这种化合物，高品质的单晶标本上进行了研究。$_2$的磁电阻（MR）很大（在$B=9$ T中的$T=1.8$ K下超过$3000\%$）并且在所研究的整个温度范围内在强场中是不饱和的。MR等温线服从Kohler型标度，指数$m$ = 1.69，不同于理想的电子-空穴补偿的情况。在外加磁场中，电阻率显示出低温平台，拓扑半金属的特征。在强磁场中，发现了具有两个主频率的良好分辨的Shubnikov-de Haas（SdH）振荡，并且它们的分析产生了$10^3\,\rm{cm^2V^{-1}s^{-1}}$量级的电荷迁移率和相当小的载流子有效质量，$0.11m_e$和$0.21m_e$。然而，提取的Berry相位点平凡的特点，参与SdH振荡的电子带。霍尔效应数据证实了PtTe $_2$的电导率具有多带特性，具有适度的电荷补偿。
英文摘要：
Platinum ditelluride has recently been characterized, based on angle-resolved photoemission spectroscopy data and electronic band structure calculations, as a possible representative of type-II Dirac semimetals. Here, we report on the magnetotransport behavior (electrical resistivity, Hall effect) in this compound, investigated on high-quality single-crystalline specimens. The magnetoresistance (MR) of PtTe$_2$ is large (over $3000\%$ at $T=1.8$ K in $B=9$ T) and unsaturated in strong fields in the entire temperature range studied. The MR isotherms obey a Kohler's type scaling with the exponent $m$ = 1.69, different from the case of ideal electron-hole compensation. In applied magnetic fields, the resistivity shows a low-temperature plateau, characteristic of topological semimetals. In strong fields, well-resolved Shubnikov - de Haas (SdH) oscillations with two principle frequencies were found, and their analysis yielded charge mobilities of the order of $10^3\,\rm{cm^2V^{-1}s^{-1}}$ and rather small effective masses of charge carriers, $0.11m_e$ and $0.21m_e$. However, the extracted Berry phases point to trivial character of the electronic bands involved in the SdH oscillations. The Hall effect data corroborated a multi-band character of the electrical conductivity in PtTe$_2$, with moderate charge compensation.
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