Dirac and Weyl Semimetallic Phases in NbN
Wan-Ju Li1*, Peng-Jen Chen1, Ting-Kuo Lee1
1Academia Sinica, Institute of Physics, Taipei, Taiwan
* Presenter:Wan-Ju Li, email:wanju1978@gmail.com
It is known that some transition metal monoarsenides/phosphides (TaAs, TaP, NbAs, and NbP)
are Weyl semimetals that can host magnetic monopoles. Motivated by these exciting findings,
we find that one of their allotropes, NbN, reveals three-dimensional Dirac points (DPs), which
can be topologically nontrivial based on the classification of Yang and Nagaosa’s work (Nat.
Commun. 5, 4898 (2014)). Using the inputs from the density functional theory (DFT), we
construct an effective Hamiltonian for the DPs of NbN by symmetry considerations. Based on
this effective model, each Dirac point splits into four Weyl points (WPs) under a Zeeman field,
consistent with the DFT bandstructures. Chiral charges are determined and some topological
properties of these DPs and WPs are discussed.

Keywords: Dirac, NbN, Weyl