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Multiple Dirac cones at the surface of the topological metal LaBi

2017; Nature Portfolio; Volume: 8; Issue: 1 Linguagem: Inglês

10.1038/ncomms13942

2041-1723

Jayita Nayak, Shu-Chun Wu, Nitesh Kumar, Chandra Shekhar, Sanjay Singh, J. Fink, Emile E. D. Rienks, Gerhard H. Fecher, S. Parkin, Binghai Yan, Claudia Felser,

Iron-based superconductors research

The rare-earth monopnictide LaBi exhibits exotic magneto-transport properties including an extremely large and anisotropic magnetoresistance. Experimental evidence for topological surface states is still missing although band inversions have been postulated to induce a topological phase in LaBi. By employing angle-resolved photoemission spectroscopy (ARPES) in conjunction with $ab~initio$ calculations, we have revealed the existence of surface states of LaBi through the observation of three Dirac cones: two coexist at the corners and one appears at the center of the Brillouin zone. The odd number of surface Dirac cones is a direct consequence of the odd number of band inversions in the bulk band structure, thereby proving that LaBi is a topological, compensated semi-metal, which is equivalent to a time-reversal invariant topological insulator. Our findings provide insight into the topological surface states of LaBi's semi-metallicity and related magneto-transport properties.