Publications Repository - Gdańsk University of Technology

A polycrystalline sample of superconducting ThI r 3 was obtained by arc-melting Th and Ir metals. Powder x-ray diffraction revealed that the compound crystalizes in a rhombohedral crystal structure (R-3m, s.g. #166) with the lattice parameters: a = 5.3394 ( 1 ) Å and c = 26.4228 ( 8 ) Å . Normal and superconducting states were studied by magnetic susceptibility, electrical resistivity, and heat capacity measurements. The results showed that ThI r 3 is a type-II superconductor (Ginzburg-Landau parameter κ = 38 ) with the critical temperature T c = 4.41 K . The heat capacity data yielded the Sommerfeld coefficient γ = 17.6 mJ / ( mo l K 2 ) and the Debye temperature Θ D = 169 K . The ratio Δ C / ( γ T c ) = 1.6 , where Δ C stands for the specific heat jump at T c , and the electron–phonon coupling constant λ e − p = 0.74 suggest that ThI r 3 is a moderate-strength superconductor. The experimental studies were supplemented by band structure calculations, which indicated that the superconductivity in ThI r 3 is governed mainly by 5 d states of iridium. The significantly smaller band-structure value of Sommerfeld coefficient as well as the experimentally observed quadratic temperature dependence of resistivity and enhanced magnetic susceptibility suggest the presence of electronic interactions in the system, which compete with superconductivity.

Authors

• dr inż. Karolina Górnicka link open in new tab ,
• Debarchan Das,
• Sylwia Gutowska,
• Bartłomiej Wiendlocha,
• dr inż. Michał Winiarski link open in new tab ,
• prof. dr hab. inż. Tomasz Klimczuk link open in new tab ,
• Dariusz Kaczorowski