Crystalline topological Dirac semimetal phase in rutile structure β′-PtO2

Abstract

Based on first-principles calculations and symmetry analysis, we propose that a transition-metal rutile oxide, in particular β′-PtO2, can host a three-dimensional topological Dirac semimetal phase. We find that β′-PtO2 possesses an inner nodal chain structure when spin-orbit coupling is neglected. Incorporating spin-orbit coupling gaps the nodal chain while preserving a single pair of three-dimensional Dirac points protected by a screw rotation symmetry. These Dirac points are created by a band inversion of two d bands, which is a realization of a Dirac semimetal phase in a correlated electron system. Moreover, a mirror plane in the momentum space carries a nontrivial mirror Chern number nM=-2, which distinguishes β′-PtO2 from the Dirac semimetals known so far, such as Na3Bi and Cd3As2. If we apply a perturbation that breaks the rotation symmetry and preserves the mirror symmetry, the Dirac points are gapped, and the system becomes a topological crystalline insulator. © 2019 American Physical Society