Type II Nodal line Semimetal

TL;DR

This paper introduces a new class of topological semimetal called type-II NLSM, characterized by tilted Weyl cones on a nodal line, and explores their magnetic properties under various interactions and fields.

Contribution

It proposes the concept of type-II NLSM based on a two-band cubic lattice model and studies their magnetic and electronic properties, including effects of magnetic fields and interactions.

Findings

Type-II NLSM features tilted Weyl cones on a nodal line.

Interaction induces various magnetic orders in bulk and surface states.

Critical point exhibits ferromagnetic order due to flat bands.

Abstract

Recently, topological semimetals become hot topic in condensed matter physics, including Dirac semimetal, Weyl semimetal, and nodal line semimetal (NLSM). In this paper, a new type of node- line semimetal - 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 nodal line become tilted. The effect of magnetic field and that of correlation on type-II NLSM are studied. In particular, after considering 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 order of surface states may exist. At critical point between type-I NLSM and type-II NLSM, arbitrary tiny interaction induces ferromagnetic order due to a flat band at Fermi surface.