Evidence of topological insulator state in the semimetal LaBi

Abstract

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 [Phys. Rev. Lett. 117, 127204 (2016)], a topologically trivial XMR semimetal, except the existence of a band inversion along the $\Gamma$-$X$ direction, with one massless and one gapped Dirac-like surface state at the $X$ and $\Gamma$ 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.

6 pages, 4 figures

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• Observation of gapped state in rare-earth monopnictide HoSb
• Complex electronic structure evolution of NdSb across the magnetic transition
• Directional effects of antiferromagnetic ordering on the electronic structure in NdSb
• Behavior of gapped and ungapped Dirac cones in an antiferromagnetic topological metal, SmBi
• Antiferromagnetic topological insulator with selectively gapped Dirac cones
• First principles investigation of topological phase in XMR material TmSb under hydrostatic pressure
• LaN Structural and Topological Transitions Driven by Temperature and Pressure
• Chiral phonons in binary compounds $A$Bi ($A$ = K, Rb, Cs) with P2${}_1$/c structure
• Temperature-dependent Fermi surface probed by Shubnikov-de Haas oscillations in topological semimetal candidates DyBi and HoBi
• Unexpected changes in the band structure within AFM1 state of CeBi
• SrPd, a candidate material with extremely large magnetoresistance
• Direct evidence of electron-hole compensation for XMR in topologically trivial YBi
• First-principles study on the electron-phonon coupling and magnetoresistance of LaBi under pressure
• Long-range magnetic order induced surface state in GdBi and DyBi
• Non-trivial topology in rare-earth monopnictides from dimensionality reduction
• Signatures of non-trivial band topology in LaAs/LaBi heterostructure
• Spin-orbital order and excitons in magnetoresistive HoBi