Investigation of LiFeAs by means of "Break-junction" Technique

Abstract

In our tunneling investigation using Andreev superconductor - normal metal - superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap ${\Delta }_L=(2.5÷3.4)$ meV and the small gap ${\Delta }_L=(0.9÷1)$ meV at $T=4.2$ K for the $T_C^{local}\approx (10.5÷14)$ K (the contact area critical temperature which deviation causes the variation of ${\Delta }_L$). The BCS-ratio is found to be $2{\Delta }_L/k_B{T}_C=(4.6÷5.6)$, whereas $2{\Delta }_S/k_B{T}_C\ll 3.52$ results from induced superconductivity in the bands with the small gap.

arXiv comment7 pages, 5 figures. Published in Pis'ma v ZhETF 95, 604-610 (2012)

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Cited by in corpus (7)

• Break-junction technique in application to layered superconductors (Review article)
• Andreev spectroscopy of iron-based superconductors: temperature dependence of the order parameters and scaling of the ${\Delta }_{L,S}$ with $T_C$
• Effect of gap anisotropy on the spin resonance peak in the superconducting state of iron-based materials
• Spin resonance peak in Fe-based superconductors with unequal gaps
• Multigap Superconductivity in GdFeAsO${}_{0.88}$ Evidenced by SnS-Andreev Spectroscopy
• Estimation of intraband and interband relative coupling constants from temperature dependences of the order parameter for two-gap superconductors
• Intrinsic Multiple Andreev Reflections in layered Th-doped Sm${}_{1-x}$Th${}_x$OFeAs