Coexistence of type-I and critical-type nodal line states in intermetallic compounds ScM (M = Cu, Ag, Au)

Abstract

In recent years, topological semimetals such as Weyl, Dirac, and nodal-line semimetals have been a hot topic in thefield of condensed matter physics. Depending on the orientation of band crossing in momentum space, topological semimetals and metals can be identi_ed as type-I or type-II. Here, we report the coexistence of two new types of topological metal phase in the ScM (M = Cu, Ag, Au) intermetallic compounds (IMCs): (1) multi-nodal-lines semimetals (above Fermi energy), (2) critical-type nodal-lines (lower than Fermi energy). The_rst case has already been investigated. So, in this paper, we focus on the second case. We_nd that these IMCs can be an existing topological metal lower than Fermi energy, which are characterized with type-I (for ScCu and ScAu) and critical-type (for ScAg) nodal-lines in the bulk and drumhead liked surface states in the absence of the spin-orbit coupling (SOC). It has also been shown that when SOC is included, these compounds are converted into topological metal materials. © 2020 Institute of Physics Publishing. All rights reserved.