Abstract
The room temperature ferromagnetic phase of the cubic antiperovskite Mn3ZnC is suggested from first-principles calculation to be a nodal line Weyl semimetal. Features in the electronic structure that are the hallmark of a nodal line Weyl state—a large density of linear band crossings near the Fermi level—can also be interpreted as signatures of a structural and/or magnetic instability. Indeed, it is known that Mn3ZnC undergoes transitions upon cooling from a paramagnetic to a cubic ferromagnetic state under ambient conditions and then further into a noncollinear ferrimagnetic tetragonal phase at a temperature between 250 K and 200 K. The existence of Weyl nodes and their destruction via structural and magnetic ordering are likely to be relevant to a range of magnetostructurally coupled materials.
Highlights
Antiperovskite carbides are a family of materials with the cubic perovskite structure and formula X3BC where X is the least electronegative element in the formula and C is carbon
Mn3GaC is known to display giant magnetoresistance5 and Ni3MgC is an 8 K superconductor, the latter rationalized by first principles calculations as being associated with a flat band (FB) with large density of states (DOS) near the Fermi level
We have shown electronic structure simulations predicting that the room temperature phase of Mn3ZnC is an exotic Weyl nodal line semimetal with nodal loops, isolated Weyl nodes, and drumhead surface states
Summary
Antiperovskite carbides are a family of materials with the cubic perovskite structure and formula X3BC where X is the least electronegative element in the formula and C is carbon (see Fig. 1). Mn3GaC is known to display giant magnetoresistance and Ni3MgC is an 8 K superconductor, the latter rationalized by first principles calculations as being associated with a flat band (FB) with large density of states (DOS) near the Fermi level.. The larger class of antiperovskites has been explored due to the prediction of topological electronic states. The Ca3PbO and Ca3BiN families include Dirac semimetals8,9— materials with a graphene-like linear-band crossing, or Dirac cone, near the Fermi level10,11—as well as topological insulators and topological crystalline insulators with a bulk band gap and metallic surface states. Magnetization and resistivity data in two recent studies on Sr3PbO and Sr3SnO provide preliminary evidence for Dirac transport and low-temperature superconductivity, respectively
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