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Evidence of topological insulator state in the semimetal LaBi

2017; American Physical Society; Volume: 95; Issue: 11 Linguagem: Inglês

10.1103/physrevb.95.115140

2469-9977

Rui Lou, Binbin Fu, Qiunan Xu, P.-J. Guo, Lingyuan Kong, L.-K. Zeng, Junzhang Ma, P. Richard, Chi Fang, Yaobo Huang, Shanshan Sun, Q. Wang, L. Wang, Y. G. Shi, Hechang Lei, Kai Liu, Hongming Weng, Tian Qian, Hong Ding, Shancai Wang,

Rare-earth and actinide compounds

By employing angle-resolved photoemission spectroscopy combined with first-principles calculations, we performed a systematic investigation on the electronic structure of LaBi, which exhibits extremely large magnetoresistance (XMR), and is theoretically predicted to possess band anticrossing with nontrivial topological properties. Here, the observations of the Fermi-surface topology and band dispersions are similar to previous studies on LaSb [L.-K. Zeng, R. Lou, D.-S. Wu, Q. N. Xu, P.-J. Guo, L.-Y. Kong, Y.-G. Zhong, J.-Z. Ma, B.-B. Fu, P. Richard, P. Wang, G. T. Liu, L. Lu, Y.-B. Huang, C. Fang, S.-S. Sun, Q. Wang, L. Wang, Y.-G. Shi, H. M. Weng, H.-C. Lei, K. Liu, S.-C. Wang, T. Qian, J.-L. Luo, and H. Ding, Phys. Rev. Lett. 117, 127204 (2016)], a topologically trivial XMR semimetal, except the existence of a band inversion along the $\mathrm{\ensuremath{\Gamma}}\text{\ensuremath{-}}X$ direction, with one massless and one gapped Dirac-like surface state at the $X$ and $\mathrm{\ensuremath{\Gamma}}$ points, respectively. The odd number of massless Dirac cones suggests that LaBi is analogous to the time-reversal ${Z}_{2}$ nontrivial topological insulator. These findings open up a new series for exploring novel topological states and investigating their evolution from the perspective of topological phase transition within the family of rare-earth monopnictides.