We thank X. Xu, V. Fatemi, E. J. Sie and S. Fang for discussions. N.G., S.-Y.X., A.K. and A.Z. acknowledge support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, DMSE (data taking and analysis) and the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF4540 (manuscript writing). Work in P.J.-H. group was supported through AFOSR grant FA9550-16-1-0382 (fabrication and measurement), as well as through the Center for the Advancement of Topological Semimetals, an Energy Frontier Research Center funded by the US Department of Energy Office of Science, Office of Basic Energy Sciences, through the Ames Laboratory under contract DE-AC02-07CH11358 (data analysis), and the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant GBMF 4541 to P.J.-H. This work made use of the Materials Research Science and Engineering Center Shared Experimental Facilities supported by the National Science Foundation (NSF) (grant number DMR-0819762). The work at Drexel University was supported by NSF through grant number ECCS-1711015. Research conducted at CHESS is supported by the NSF via awards DMR-1332208 and DMR-1829070. Work at CMU was supported by the Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division, through grant number DE-SC0012509. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by MEXT, Japan, JSPS KAKENHI grant numbers JP18K19136 and CREST (JPMJCR15F3), JST. T.-R.C. was supported by the Young Scholar Fellowship Program of the Ministry of Science and Technology (MOST) in Taiwan, under a MOST grant for the Columbus Program MOST108-2636-M-006-002, National Cheng Kung University, Taiwan, and National Center for Theoretical Sciences, Taiwan. This work was supported partially by MOST, Taiwan, via grant MOST107-2627-E-006-001. This research was supported in part by a Higher Education Sprout Project, Ministry of Education from the Headquarters of University Advancement at National Cheng Kung University (NCKU). S.-M.H. acknowledges support by the Ministry of Science and Technology (MoST) in Taiwan under grant number 105-2112-M-110-014-MY3. H.L. acknowledges Academia Sinica, Taiwan for support under Innovative Materials and Analysis Technology Exploration (AS-iMATE-107-11).