Topological semimetal in honeycomb lattice LnSI

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 114; no. 40; pp. 10596 - 10600
• Main Authors: Nie, Simin, Xu, Gang, Prinz, Fritz B., Zhang, Shou-cheng
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.10.2017; Proceedings of the National Academy of Sciences
• Subjects: Condensed matter physics; Electronics; Elementary particles; Fermions; Handedness; Honeycomb construction; Lattice theory; Lattices; Metalloids; Physical Sciences; Physics; Standard model (particle physics); Topological insulators; Topology; topological insulator; Fermi arc; honeycomb lattice; ideal Weyl fermion; nodal-line semimetal
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1713261114

Recognized as elementary particles in the standard model, Weyl fermions in condensed matter have received growing attention. However, most of the previously reported Weyl semimetals exhibit rather complicated electronic structures that, in turn, may have raised questions regarding the underlying physics. Here, we report promising topological phases that can be realized in specific honeycomb lattices, including ideal Weyl semimetal structures, 3D strong topological insulators, and nodal-line semimetal configurations. In particular, we highlight a semimetal featuring both Weyl nodes and nodal lines. Guided by this model, we showed that GdSI, the long-perceived ideal Weyl semimetal, has two pairs of Weyl nodes residing at the Fermi level and that LuSI (YSI) is a 3D strong topological insulator with the right-handed helical surface states. Our work provides a mechanism to study topological semimetals and proposes a platform for exploring the physics of Weyl semimetals as well as related device designs.