  The relation between the spin-density-wave (SDW) and superconducting order is
a central topic in current research on the FeAs-based high Tc superconductors.
Conflicting results exist in the LaFeAs(O,F)-class of materials, for which
whether the SDW and superconductivity are mutually exclusive or they can
coexist has not been settled. Here we show that for the (Ba,K)Fe2As2 system,
the SDW and superconductivity can coexist in an extended range of compositions.
The availability of single crystalline samples and high value of the energy
gaps would make the materials a model system to investigate the high Tc
ferropnictide superconductivity.
