Abstract
We analyze the symmetry and topological features of a family of materials closely related to penta-graphene, derived from it by adsorption or substitution of different atoms. Our description is based on a novel approach, called topological quantum chemistry, that allows to characterize the topology of the electronic bands, based on the mapping between real and reciprocal space. In particular, by adsorption of alkaline (Li or Na) atoms we obtain a nodal line metal at room temperature, with a continuum of Dirac points around the perimeter of the Brillouin zone. This behavior is also observed in some substitutional derivatives of penta-graphene, such as penta-PC2. Breaking of time-reversal symmetry can be achieved by the use of magnetic atoms; we study penta-MnC2, which also presents spin-orbit coupling and reveals a Chern insulator phase. We find that for this family of materials, symmetry is the source of protection for metallic and nontrivial topological phases that can be associated to the presence of fractional band filling, spin-orbit coupling and time-reversal symmetry breaking.
Highlights
Topological phases of materials due to spatial and non spatial symmetries are the subject of enormous attention, both from the fundamental and the applied viewpoint
We find an evolution of the electronic band structure from a general nodal line located at the boundary of Brillouin zone (BZ), through a point-like Dirac node near the Fermi level at the corner of the BZ, to topologically nontrivial phases in presence of spin-orbit coupling (SOC) plus time-reversal symmetry (TRS) breaking
We have studied a set of materials sharing a space group structure that we dub penta-materials
Summary
Topological phases of materials due to spatial and non spatial symmetries are the subject of enormous attention, both from the fundamental and the applied viewpoint. We present a complete TQC analysis and ab initio calculations that explore the topological nature of these penta-materials, analyzing them from the unifying perspective of group theory. We find an evolution of the electronic band structure from a general nodal line located at the boundary of Brillouin zone (BZ), through a point-like Dirac node near the Fermi level at the corner of the BZ, to topologically nontrivial phases in presence of spin-orbit coupling (SOC) plus time-reversal symmetry (TRS) breaking.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
