Li Shiyan

Nodeless superconducting gaps in Ca

The in-plane thermal conductivity of the iron-based superconductor Ca10(Pt4-δAs8)((Fe1-xPtx)2As2)5 single crystal (“10-4-8”, Tc = 22 K) was measured down to 80 mK. In a zero field, the residual linear term κ0/T is negligible, suggesting the nodeless superconducting gaps in this multiband compound. In the magnetic fields, κ0/T increases rapidly, which mimics the multiband superconductor NbSe2 and LuNi2B2C with highly anisotropic gap. Such a field dependence of κ0/T is an evidence for the multiple superconducting gaps with quite different magnitudes or highly anisotropic gap. Compared with the London penetration depth results of the Ca10(Pt4-δAs8)((Fe1-xPtx)2As2)5 (“10-3-8”) compound, the 10-4-8 and 10-3-8 compounds may have a similar superconducting gap structure.