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Spectroscopic evidence on classification of ferromagnetic Co3Sn2S2 as a magnetic Weyl semimetal


  Pranab Kumar Nag [1]  ,  Noam Morali [1]  ,  Rajib Batabyal [1]  ,  Enke Liu [2,3]  ,  Qiunan Xu [2]  ,  Yan Sun [2]  ,  Binghai Yan [1]  ,  Claudia Felser [2,4,5]  ,  Nurit Avraham [1]  ,  Haim Beidenkopf [1]  
 [1] Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
[2] Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
[3] Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
[4] John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
[5] Department of Physics, Harvard University, Cambridge, MA 02138, USA

”Fermi arc” states are the characteristic features of topological Weyl semimetals. They connect the surface projection of the bulk Weyl nodes. However their actual connectivity remains ambiguous in the presence of multiple pairs of surface projected Weyl nodes as well as in the presence of different surface potentials. We use Fourier-transform scanning tunneling microscopy and spectroscopy technique to verify the classification of the ferromagnetic Co3Sn2S2 as a time reversal symmetry broken magnetic Weyl semimetal. By studying three different surface terminations the Fermi-arc connectivity and the Fermi-arc contour in Co3Sn2S2 have been found to vary with the different surface potential. While intra-Brillouin zone connectivity is observed on the Sn surface, the Fermi-arcs connect Weyl nodes across the Brillouin zone edge on the Co surface. On the S termination, the Fermi-arcs hybridize with non-topological bulk and therefore their connectivity remain obscured.