Experimental Evidence of Topological Surface States in Mg3Bi2 Films Grown by Molecular Beam Epitaxy  

作　　者：Tong Zhou Xie-Gang Zhu Mingyu Tong Yun Zhang Xue-Bing Luo Xiangnan Xie() Wei Feng Qiuyun Chen Shiyong Tan Zhen-Yu Wang Tian Jiang Yuhua Tang Xin-Chun Lai Xuejun Yang 周侗;朱燮刚;童明玉;张云;罗学兵;谢向男;冯卫;陈秋云;谭世勇;王振宇;江天;唐玉华;赖新春;杨学军(State Key Laboratory of High Performance Computing,College of Computer,National University of Defense Technology,Changsha 410073;Science and Technology on Surface Physics and Chemistry Laboratory,Jiangyou 621908;National Innovation Institute of Defense Technology,Academy of Military Sciences PLA China,Beijing 100010;Institute of Materials,China Academy of Engineering Physics,Mianyang 621700;College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073;Academy of Military Sciences PLA China,Beijing 100010;Beijing Academy of Quantum Information Sciences,Beijing 100084)

机构地区：[1]State Key Laboratory of High Performance Computing,College of Computer,National University of Defense Technology,Changsha 410073 [2]Science and Technology on Surface Physics and Chemistry Laboratory,Jiangyou 621908 [3]National Innovation Institute of Defense Technology,Academy of Military Sciences PLA China,Beijing 100010 [4]Institute of Materials,China Academy of Engineering Physics,Mianyang 621700 [5]College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073 [6]Academy of Military Sciences PLA China,Beijing 100010 [7]Beijing Academy of Quantum Information Sciences,Beijing 100084

出　　处：《Chinese Physics Letters》2019年第11期65-69,共5页中国物理快报（英文版）

基　　金：Supported 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 2012YQ13012508;the General Program of Beijing Academy of Quantum Information Sciences under Grant No Y18G17;the Youth Talent Lifting Project under Grant No 17-JCJQ-QT-004

摘　　要：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 Mg3 Bi2 films are grown by molecular beam epitaxy(MBE). By in-situ angle resolved photoemission spectroscopy(ARPES), a pair of surface resonance bands around theГ 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(2 D) 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.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 Mg3 Bi2 films are grown by molecular beam epitaxy（MBE）. By in-situ angle resolved photoemission spectroscopy（ARPES）, a pair of surface resonance bands around the■ 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（2 D） 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.

关 键 词：BANDS TOPOLOGICAL terminated 

分 类 号：O46[理学—电子物理学]