Zhang Cheng-Long, Xu Su-Yang, Belopolski Ilya, Yuan Zhujun, Lin Ziquan, Tong Bingbing, Bian Guang, Alidoust Nasser, Lee Chi-Cheng, Huang Shin-Ming, Chang Tay-Rong, Chang Guoqing, Hsu Chuang-Han, Jeng Horng-Tay, Neupane Madhab, Sanchez Daniel S, Zheng Hao, Wang Junfeng, Lin Hsin, Zhang Chi, Lu Hai-Zhou, Shen Shun-Qing, Neupert Titus, Zahid Hasan M, Jia Shuang
International Center for Quantum Materials, School of Physics, Peking University, Beijing, China.
Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Nat Commun. 2016 Feb 25;7:10735. doi: 10.1038/ncomms10735.
Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, that is, unlike most metals whose resistivity increases under an external magnetic field, we observe that our high mobility TaAs samples become more conductive as a magnetic field is applied along the direction of the current for certain ranges of the field strength. We present systematically detailed data and careful analyses, which allow us to exclude other possible origins of the observed negative magnetoresistance. Our transport data, corroborated by photoemission measurements, first-principles calculations and theoretical analyses, collectively demonstrate signatures of the Weyl fermion chiral anomaly in the magneto-transport of TaAs.
外尔半金属实现了固态物理学中的外尔费米子。在外尔半金属所引发的所有物理现象中，手征反常是最为奇特的一种。在此，我们报告了在首个外尔半金属TaAs的磁输运测量中手征反常的特征。我们展示了在平行电场和磁场下的负磁阻现象，也就是说，与大多数金属在外部磁场下电阻率增加不同，我们观察到对于特定场强范围，当磁场沿电流方向施加时，我们的高迁移率TaAs样品导电性变得更强。我们呈现了系统详细的数据和仔细的分析，这使我们能够排除观察到的负磁阻的其他可能来源。我们的输运数据，得到了光电子能谱测量、第一性原理计算和理论分析的证实，共同证明了TaAs磁输运中外尔费米子手征反常的特征。
