Robustness of the semimetal state of Na3Bi and Cd3As2 against Coulomb interactions

Article

关键词: TOPOLOGICAL PHASE-TRANSITION;    DIRAC SEMIMETAL;    EXCITONIC INSTABILITY;    OPTICAL-PROPERTIES;    WEYL SEMIMETALS;    GRAPHENE;    FERMIONS;    DISCOVERY;    INSULATOR;   

DOI  :  10.1103/PhysRevB.97.155122

来源: SCIE

【 摘 要 】

We study the excitonic semimetal-insulator quantum phase transition in a three-dimensional Dirac semimetal in which the fermion dispersion is strongly anisotropic. After solving the Dyson-Schwinger equation for the excitonic gap, we obtain a global phase diagram in the plane spanned by the parameter for Coulomb interaction strength and the parameter for fermion velocity anisotropy. We find that excitonic gap generation is promoted as the interaction becomes stronger but is suppressed if the anisotropy increases. Applying our results to two realistic three-dimensional Dirac semimetals Na3Bi and Cd3As2, we establish that their exact zero-temperature ground state is gapless semimetal rather than excitonic insulator. Moreover, these two materials are far from the excitonic quantum critical point, and thus there should not be any observable evidence for excitonic insulating behavior. This conclusion is in general agreement with the existing experiments of Na3Bi and Cd3As2.

【 授权许可】

Free