Experimental determination of superconducting parameters for the intermetallic perovskite superconductor MgCNi3

Zhiqiang Mao, M. M. Rosario, K. D. Nelson, K. Wu, I. G. Deac, P. Schiffer, Ying Liu, T. He, K. A. Regan, R. J. Cava

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Abstract

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 languageEnglish (US)
Article number094502
Pages (from-to)945021-945026
Number of pages6
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume67
Issue number9
Publication statusPublished - Mar 1 2003

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Mao, Zhiqiang ; Rosario, M. M. ; Nelson, K. D. ; Wu, K. ; Deac, I. G. ; Schiffer, P. ; Liu, Ying ; He, T. ; Regan, K. A. ; Cava, R. J. / Experimental determination of superconducting parameters for the intermetallic perovskite superconductor MgCNi3. In: Physical Review B - Condensed Matter and Materials Physics. 2003 ; Vol. 67, No. 9. pp. 945021-945026.