Experimental Evidence of Topological Surface States in Mg3Bi2 Films Grown by Molecular Beam EpitaxySupported by the Science Challenge Project under Grant No TZ2016004, the Opening Foundation of State Key Laboratory of High Performance Computing under Grant No 201601-02, the Foundation of President of CAEP under Grant No 201501040, the Natural Science Foundation of Hunan Province under Grant No 2016JJ1021, the National Basic Research Program of China under Grant Nos 2015CB921303 and 2012YQ1301250

• Published in: Chinese physics letters 2019-11, Vol.36 (11)
• Main Authors: Zhou, Tong, Zhu, Xie-Gang, Tong, Mingyu, Zhang, Yun, Luo, Xue-Bing, Xie, Xiangnan, Feng, Wei, Chen, Qiuyun, Tan, Shiyong, Wang, Zhen-Yu, Jiang, Tian, Tang, Yuhua, Lai, Xin-Chun, Yang, Xuejun
• Format: Article
• Language: English
• ISSN: 0256-307X
• DOI: 10.1088/0256-307X/36/11/117303

Nodal line semimetal (NLS) is a new quantum state hosting one-dimensional closed loops formed by the crossing of two bands. The so-called type-II NLS means that these two crossing bands have the same sign in their slopes along the radial direction of the loop, which requires that the crossing bands are either right-tilted or left-tilted at the same time. According to the theoretical prediction, Mg3Bi2 is an ideal candidate for studying the type-II NLS by tuning its spin-orbit coupling (SOC). High-quality Mg3Bi2 films are grown by molecular beam epitaxy (MBE). By in-situ angle resolved photoemission spectroscopy (ARPES), a pair of surface resonance bands around the Γ¯ point are clearly seen. This shows that Mg3Bi2 films grown by MBE are Mg(1)-terminated by comparing the ARPES spectra with the first principles calculations results. Moreover, the temperature dependent weak anti-localization effect in Mg3Bi2 films is observed under magneto-transport measurements, which shows clear two-dimensional (2D) e-e scattering characteristics by fitting with the Hikami-Larkin-Nagaoka model. Therefore, by combining with ARPES, magneto-transport measurements and the first principles calculations, this work proves that Mg3Bi2 is a semimetal with topological surface states. This paves the way for Mg3Bi2 to be used as an ideal material platform to study the exotic features of type-II nodal line semimetals and the topological phase transition by tuning its SOC.