Observation of Fermi arc surface states in a topological metal

TLDR

Topological insulators exhibit robust conducting surface states, while theorists predict a distinct surface state in gapless three‑dimensional topological Dirac semimetals. The authors employed photoemission spectroscopy to map Na3Bi’s band structure and identify the predicted surface state. The detection of the surface state confirms theoretical predictions and may provide deeper insight into topological matter. Xu et al., Science, p.

Abstract

Nailing down the topology of a semimetal Topological insulators are exotic materials that have a conducting surface state that can withstand certain types of material imperfection. Theoreticians have predicted a different kind of surface state in related three-dimensional topological Dirac semimetals, which do not have an energy gap in the band structure of the bulk. Xu et al. used photoemission spectroscopy to map out the band structure of the material Na 3 Bi and detected the predicted surface state. Their results may lead to further insights into the physics of topological matter. Science , this issue p. 294