Superconducting energy gap in MgCNi3 single crystals: Point-contact spectroscopy and specific-heat measurements

Article

关键词: CRITICAL-FIELD HC2;    PURITY DEPENDENCE;    TEMPERATURE;   

DOI  :  10.1103/PhysRevB.83.104511

来源: SCIE

【 摘 要 】

Specific heat has been measured down to 600 mK and up to 8 T by highly sensitive ac microcalorimetry on MgCNi3 single crystals with T-c approximate to 7 K. Exponential decay of the electronic specific heat at low temperatures proved that a superconducting energy gap is fully open on the whole Fermi surface, in agreement with our previous magnetic penetration depth measurements on the same crystals. The specific-heat data analysis shows consistently the strong-coupling strength 2 Delta/k(B)T(c) approximate to 4. This scenario is supported by the direct measurements of the gap via the point-contact spectroscopy. Moreover, the spectroscopy measurements show a decrease in the critical temperature at the sample surface, which accounts for the observed differences of the superfluid density deduced from the measurements by different techniques.

【 授权许可】

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