Bulk superconductivity in transition metal oxide TaO.

The discovery of coexistence of bulk superconductivity and nontrivial topological bands in the compounds, such as LaO and NbC, with a rocksalt structure, motivates us to study the physical properties of TaO with the same structure. Based on preparing successfully TaO polycrystalline sample, we measured its resistivity, magnetization, and specific heat. It was first found that TaO is a type-II superconductor with the critical temperature T c = 6.20 K and the Ginzburg–Landau parameter κ G L (0) = 16.2. The estimated electron–phonon coupling constant λ e p (0.62) and the specific heat jump Δ C e l / γ n T c (0.56) demonstrate that TaO is a weak-coupling phonon-mediated superconductor. The lack of single crystal sample impedes us to study experimentally its properties related to the electronic band topology, which is the subject of endeavor in the future. • TaO polycrystalline sample were first successfully synthesized. • It was first found that TaO is a type-II superconductor. • TaO is a weak-coupling phonon-mediated conventional superconductor. [ABSTRACT FROM AUTHOR]