We have measured upper-critical-field Hc2, specific heat C, and tunneling spectra of the intermetallic perovskite superconductor MgCNi3 with a superconducting transition temperature Tc,≈7.6 K. Based on these measurements and relevant theoretical relations, we have evaluated various superconducting parameters for this material, including the thermodynamic critical field Hc(0), coherence length ξ(0), penetration depth λ(0), lower-critical-field Hc1(0), and Ginzburg-Landau parameter κ(0). From the specific heat, we obtain the Debye temperature ΘD≈284 K. We find ajump of ΔClλTc=2.1 at Tc (where γ is the normal-state electronic specific coefficient), which is larger than the weak-coupling BCS value of 1.43, suggesting that MgCNi3 may be a strong-coupling superconductor. In addition, we observed a pronounced zero-bias conductance peak (ZBCP) in the tunneling spectra. We discuss the possible physical origins of the observed ZBCP.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Mar 1 2003|