Pressure is a powerful tool of introducing intriguing physical phenomena, unveiling new physics, as well as discovering new theory. Topological semimetal is a class of semimetals co-existing of non-trivial topological states and trivial bulk states in electronic band structure. There still exist two important unveiled issues in the studies of DSM materials. How will these two different band structures evolutes under pressure, and how can the band structure affect its transport properties? A recent high pressure study on the type II Dirac Semimetal (DSM) PtTe2 reveals that the trivial band structure, other than the Dirac nodes, plays a keynote role in its transport properties.
Recently, Pressure-induced Lifshitz transition in the type II Dirac semimetal PtTe2 has been published on SCIENCE CHINA Physics, Mechanics & Astronomy 62(4), 048211 (2019), of which the first author is Fengliang Liu, a PhD student in Physics Department, under the supervising of Prof. Jian Shen from Fudan University, and Prof. Wenge Yang from HPSTAR. In addition, collaborators from Tsinghua University also provide significant contributions to this work, as Prof. Wenhui Duan's group on the DFT calculations, and Prof. Shuyun Zhou's group on the crystallization of PtTe2 samples. The paper studied the evolutions of lattice structure, transport properties and electronic band structures of pressurized PtTe2. Critical transition in transport was observed around 20 GPa, without any lattice structure phase transitions under pressure. In addition, DFT calculation gives a clear picture of pressure induced DSM state annihilations around 10 GPa, and a pressure induced Lifshitz transition at the trivial band near Fermi Surface around 20 GPa. Finally, a conclusion was made that the trivial band structure plays a keynote role in its transport properties in PtTe2, a type II DSM compound. The main results are shown in Figure 1.
Previously, the non-trivial topological node is widely studied both experimentally and theoretically, while the significance of the trivial band structure is rarely recognized. This paper combines the DFT calculations and transport measurement together with the XRD results, successfully explaining the transition in a transport, and additionally unveiling the significance of the trivial band structure in PtTe2. The robust lattice structure and sensitive of pressure dependence magnetoresistance indicate a promising way to design sensitive electronic devices and the new sensors under extremely conditions (high pressure, low temperature and high magnetic field) is applicable in this PtTe2 family related DSM compounds.
This work is supported by The National Key Research and Development Program of China (Grant No. 2016YFA0300702), the National Basic Research Program of China (973 Program) (Grant No. 2014CB921104), the Shanghai Municipal Natural Science Foundation (Grant Nos. 18JC1411400, 18ZR1403200, and 17ZR1442400), NSAF (Grant No. U1530402), the National Natural Science Foundation of China (Grant No. 11674188), the China Postdoctoral Science Foundation (Grant No. 2017M610221), the Shanghai Sailing Program (Grant No. 17YF1429000) and the National Postdoctoral Program for Innovative Talents (Grant No. BX201600036).
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FengLiang Liu, JiaHeng Li, KeNan Zhang, Shang Peng, HuaQing Huang, MingZhe Yan, NaNa Li, Qian Zhang, SongHao Guo, XuJie Lü, Peng Cai, LiFeng Yin, ShuYun Zhou, WenHui Duan, Jian Shen, and WenGe Yang, Pressure-induced Lifshitz transition in the type II Dirac semimetal PtTe2. Sci. China-Phys. Mech. Astron. 62(4), 048211 (2019), https://doi.org/10.1007/s11433-018-9319-3.