High-pressure synthesis and superconductivity of the novel laves phase BaIr2

Superconductors comprising 5d transition metals of Ir and Pt have been widely explored because they the potential unique superconductivity caused by strong spin-orbit interaction (SOI). We successfully synthesized BaIr2, last Laves phase remaining unsynthesized in MgCu2-type AM2 (A = Ca, Sr, Ba; M Rh, Pd, Ir, Pt). BaIr2 was crystallized at 925 C under a pressure 3.3 GPa via solid-state reaction between Ba powders; it found to longest a-lattice constant 8.038(1) A among AM2. exhibited bulk temperature (Tc) 2.7 K. type-II superconductor with an upper critical field 67.7 kOe, which above Pauli paramagnetic limit (50 kOe). The electron-phonon coupling normalized specific heat jump were measured be 0.63 1.2, respectively, indicating that is weak-coupling superconductor. electronic-structure calculations for revealed Ir-5d states are dominant Fermi energy (EF) density EF strongly affected SOI as case CaIr2 SrIr2.