Transition metal oxides topological Dirac semimetals

Abstract: Topological Dirac semimetals (DSMs) exhibit nodal points through which energy bands disperse linearly in three-dimensional (3D) momentum space, a 3D analogue of graphene. The first experimentally confirmed DSMs with a pair of Dirac points (DPs), Na3Bi and Cd3As2, show topological surface Fermi arc states and exotic magneto-transport properties, boosting the interest in the search for stable and nontoxic DSM materials. In this talk, we will start with a general introduction to this fascinating field and explain, based on the ab-initio band structure calculations, how to characterize topological nontrivial materials. By applying this methodology, we further predict a family of palladium and platinum oxides as robust 3D DSMs. We show that along three unit axes of the cubic lattice there exist three pairs of DPs, which are linked by Fermi arcs on the surface. The Fermi arcs display a Lifshitz transition from a heart- to a diamond-shape upon varying the chemical potential. Corresponding oxides are already available as high-quality single crystals, which is an excellent precondition for the verification of our prediction by photoemission and magneto-transport experiments. Our findings not only predict a number of much robust 3D DSM candidates but also extend DSMs to transition metal oxides, a versatile family of materials, which provides an ideal platform to investigate the interplay between DSMs and electronic correlations.