Superconductivity in ternary Mg₄Pd₇As₆

We report the synthesis and characterization of a new compound Mg₄Pd₇As₆, which was found to be a superconductor with Tc=5.45~K. Powder X-ray diffraction confirms the U₄Re₇Si₆ structure (space group $Im$-$3m$, no. 229) with the lattice parameter a = 8.2572(1)~. Magnetization, specific heat, and electrical resistivity measurements indicate that it is a moderate-coupling (λ = 0.72) type-II superconductor. The electronic and phonon structures are calculated, highlighting the importance of antibonding Pd-As interactions in determining the properties of this material. The calculated electron-phonon copling parameter λ = 0.76 agrees very well with the experimental finding, which confirms the conventional pairing mechanism in Mg₄Pd₇As₆.