Superconducting state coexisting with a phase-separated static magnetic order in (Ba,K)Fe2As2, (Sr,Na)Fe2As2, and CaFe2As2

By muon spin-relaxation measurements on single-crystal specimens, we show that superconductivity in the AFe2As2 (A=Ca,Ba,Sr) systems, in both the cases of composition and pressure tunings, coexists with a strong static magnetic order in a partial volume fraction. The superfluid response from the remaining paramagnetic volume fraction of (Ba0.5K0.5)Fe2As2 exhibits a nearly linear variation in T at low temperatures, suggesting an anisotropic energy gap with line nodes and/or multigap effects.