Detail:
Abstract: Topological semimetals (TSMs) have attracted great attentions in condensed matter physics. However, the search of ideal TSMs that only the desired quasi-particles can exist around the Fermi level is still a big challenging. Taking triple-point TSM as an example, we demonstrate that the band crossing between antibonding s orbtial and bonding p orbital along a C3v symmetry can realize an ideal triple-point band crossing. By considering the general band formation model around conduction band minimum and valence band maximum in an ionic semiconductor, we have successfully targeted the ideal triple-point TSMs in NaCu3Te2 family compounds. Thanks to the ideal band crossing properties, we can further analysis the evolution of Fermi arc from Dirac to triple-point to Weyl semimetals for the first time. Recently, we have also extend the band crossing model from 0D point or 1D line to a 2D sphere in a 3D crystal, which may form a Dirac-nodal-sphere (DNS) system with unusual electronic properties. We also suggested several material candidates to realize such DNS states.
