Type-II nodal line semimetal

Abstract

Recently, topological semimetals have become a hot topic in condensed matter physics, including Dirac semimetals, Weyl semimetals, and nodal line semimetals (NLSMs). In this paper, a new type of NLSM—type-II NLSM—is proposed based on a two-band cubic lattice model. For type-II NLSM, the zero energy bulk states have a closed loop in momentum space but the (local) Weyl cones on the nodal line become tilted. The effect of the magnetic field and that of the correlation on type-II NLSM are studied. In particular, after considering the repulsive interaction and additional spin degrees of freedom, different types of long range magnetic orders appear in bulk states. In addition, the interaction-induced ferromagnetic (FM) order of surface states may exist. At a critical point between type-I NLSM and type-II NLSM, arbitrary tiny interactions induce FM order due to a flat band at the Fermi surface.

Keywords

• topological semimetal
• magnetic order parameter
• strongly correlation system