Investigation of LiFeAs by means of "Break-junction" technique
S. A. Kuzmichev+, T. E. Shanygina+°, I. V. Morozov+, A. I. Boltalin+, M. V. Roslova+, S. Wurmehl×, B. Büchner×
+Lomonosov Moscow State University, 119991 Moscow, Russia
°Lebedev Physical Institute of the RAS, 119991 Moscow, Russia
×IFW-Dresden, Institute for Solid State Research, D-01171 Dresden, Germany
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 Δ L=(2.5-3.4) meV and the small gap
Δ L=(0.9-1) meV at T = 4.2 K for the
K
(the contact area critical temperature which deviation causes the
variation of Δ L). The BCS-ratio is found to be
2Δ L/k BT C=4.6-5.6, whereas
results from induced
superconductivity in the bands with the small gap.