High-resolution magnetic penetration depth and inhomogeneities in   locally noncentrosymmetric SrPtAs
  We present a magnetic-penetration-depth study on polycrystalline and granular samples of SrPtAs, a pnictide superconductor with a hexagonal structure containing PtAs layers that individually break inversion symmetry (local noncentrosymmetry). Compact samples show a clear-cut s-wave-type BCS behavior, which we consider to be the intrinsic penetration depth of SrPtAs. Granular samples display a sample-dependent second diamagnetic drop, attributed to the intergrain coupling. Our experimental results point to a nodeless isotropic superconducting energy gap in SrPtAs, which puts strong constraints on the driven mechanism for superconductivity and the order parameter symmetry of this compound. 
J. F. Landaeta, S. V. Taylor, I. Bonalde, C. Rojas, Y. Nishikubo, K.   Kudo, and M. Nohara
cond-mat.supr-con