Tunable double-Weyl Fermion semimetal state in the SrSi2 materials class

Bahadur Singh; Guoqing Chang; Tay-Rong Chang; Shin-Ming Huang; Chenliang Su; Ming-Chieh Lin; Hsin Lin; Arun Bansil

doi:10.1038/s41598-018-28644-y

Tunable double-Weyl Fermion semimetal state in the SrSi₂ materials class

Sci Rep. 2018 Jul 12;8(1):10540. doi: 10.1038/s41598-018-28644-y.

Authors

Bahadur Singh^{1

2}, Guoqing Chang^{2

3

4}, Tay-Rong Chang⁵, Shin-Ming Huang⁶, Chenliang Su⁷, Ming-Chieh Lin⁸, Hsin Lin^{9

10

11}, Arun Bansil¹²

Affiliations

¹ SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D Materials Information Functional Devices and Systems of Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, ShenZhen, 518060, China.
² Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore.
³ Department of Physics, National University of Singapore, Singapore, 117546, Singapore.
⁴ Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
⁵ Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan.
⁶ Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan.
⁷ SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science & Technology, Engineering Technology Research Center for 2D Materials Information Functional Devices and Systems of Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, ShenZhen, 518060, China. chmsuc@szu.edu.cn.
⁸ Multidisciplinary Computational Laboratory, Department of Electrical and Biomedical Engineering, Hanyang University, Seoul, 04763, South Korea. mclin@hanyang.ac.kr.
⁹ Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, 117546, Singapore. nilnish@gmail.com.
¹⁰ Department of Physics, National University of Singapore, Singapore, 117546, Singapore. nilnish@gmail.com.
¹¹ Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan. nilnish@gmail.com.
¹² Department of Physics, Northeastern University, Boston, Massachusetts, 02115, USA.

Abstract

We discuss first-principles topological electronic structure of noncentrosymmetric SrSi₂ materials class based on the hybrid exchange-correlation functional. Topological phase diagram of SrSi₂ is mapped out as a function of the lattice constant with focus on the semimetal order. A tunable double-Weyl Fermion state in Sr_1-xCa_xSi₂ and Sr_1-xBa_xSi₂ alloys is identified. Ca doping in SrSi₂ is shown to yield a double-Weyl semimetal with a large Fermi arc length, while Ba doping leads to a transition from the topological semimetal to a gapped insulator state. Our study indicates that SrSi₂ materials family could provide an interesting platform for accessing the unique topological properties of Weyl semimetals.