Superconductivity in LiGa2Ir Heusler type compound with VEC = 16

• Published in: Scientific reports 2021-08, Vol.11 (1), p.16517-16517, Article 16517
• Main Authors: Górnicka, Karolina, Kuderowicz, Gabriel, Winiarski, Michał J., Wiendlocha, Bartłomiej, Klimczuk, Tomasz
• Format: Article
• Language: English
• Subjects: 639/301/1034; 639/301/119; Crystal structure; Electrical resistivity; Heat; Humanities and Social Sciences; Magnetic fields; Magnetic susceptibility; multidisciplinary; Physics; Science; Science (multidisciplinary); Specific heat; X-ray diffraction
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-95944-1

Polycrystalline LiGa 2 Ir 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 T c  = 2.94 K was confirmed by detailed heat capacity studies. The measurements indicate that LiGa 2 Ir is a weak-coupling type-II superconductor ( λ e–p  = 0.57, Δ C/ γ T c  = 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 λ e–p  = 0.68 confirms the electron–phonon mechanism for the superconductivity. LiGa 2 Ir and recently reported isoelectronic LiGa 2 Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC = 16.