Polycrystalline LiGa2Ir has been prepared by a solid state reaction method. A Rietveld refinement of powder x-ray diffraction data confirms a previously reported Heusler-type crystal structure (space group Fm-3m, No. 225) with lattice parameter a = 6.0322(1) Å. The normal and superconducting state properties were studied by magnetic susceptibility, heat capacity, and electrical resistivity techniques. A bulk superconductivity with Tc = 2.94 K was confirmed by detailed heat capacity studies. The measurements indicate that LiGa2Ir is a weak-coupling type-II superconductor ($${\uplambda }$$ λ e–p = 0.57, $${\Delta }$$ Δ C/$${\upgamma }$$ γ Tc = 1.4). Electronic structure, lattice dynamics, and the electron–phonon interaction are studied from first principles calculations. Ir and two Ga atoms equally contribute to the Fermi surface with a minor contribution from Li. The phonon spectrum contains separated high frequency Li modes, which are seen clearly as an Einstein-like contribution in the specific heat. The calculated electron–phonon coupling constant $${\uplambda }$$ λ e–p = 0.68 confirms the electron–phonon mechanism for the superconductivity. LiGa2Ir and recently reported isoelectronic LiGa2Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC = 16.

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We report the synthesis and physical properties of a new full Heusler compound, MgPd2Sb, which we found to show superconductivity below Tc = 2.2 K. MgPd2Sb was obtained by a two-step solid state reaction method and its purity and cubic crystal structure (F m-3m, a = 6.4523(1) Å) were confirmed by powder x-ray diffraction. Normal and superconducting states were studied by electrical resistivity, magnetic susceptibility and heat capacity measurements. The results show that MgPd2Sb is a type-II, weak coupling superconductor (λep = 0.56). The observed pressure dependence of Tc (ΔTc/p ≈ -0.23 K/GPa) is one of the strongest reported for a superconducting Heusler compound. The electronic structure, phonons and electron-phonon coupling in MgPd2Sb were theoretically investigated. The obtained results are in agreement with the experiment, confirming the electron-phonon coupling mechanism of superconductivity. We compare the superconducting parameters to those of all reported Heusler-type superconductors.

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