Density of States in the 3D System with Semimetallic Nodal-Loop and Insulating Gapped Phase

We investigate a single-particle density of states in the three-dimensional system described by effective two-band Hamiltonian, which describes a ground state in two distant electronic phases: the semimetalic nodal-loop phase and the insulating gapped phase. An analysis of valence bands and Fermi surfaces in both phases indicates that the density of states crucially depends on the parameter in the Hamiltonian of the system that controls a topological alternation of the Fermi surface. The signature of that alternation is expected to play an important role in all quantities closely related to the density of electronic states, such as charge transport and the optical conductivity of the system for example.