Superconductivity and correlated Fermi liquid behavior in noncentrosymmetric Ca 3 Ir 4 Ge 4

Abstract

We report the structure and the elementary physical properties of Ca3Ir4Ge4. This compound crystallizes in the cubic, noncentrosymmetric Na3Pt4Ge4 structure type with the space group I4̄3m and the unit cell dimension a=7.56895(4) Å. We find that Ca3Ir4Ge4 is a superconductor with a critical temperature of Tcâ‰1.8 K. The bulk character of the superconducting state is evidenced by the occurrence of a well developed discontinuity in the specific heat at Tc with Î"C/Tcâ‰38 mJ molâ1 Kâ2. Well above Tc, the compound is a weakly paramagnetic metal with Fermi liquid behavior. The low-temperature specific-heat and resistivity measurements reveal a Kadowaki-Woods ratio comparable to that of heavy fermion materials. Furthermore, the magnetization measurements show a Stoner enhancement factor of 0.57. These findings are indicators for significant electron-electron correlation in this compound. © 2014 American Physical Society.