  Single crystals of Ba0.6K0.4Fe2As2 with excellent quality have been
successfully grown without fluxing agent through a simple one-step method for
the first time. X-ray diffraction patterns demonstrate that the samples have
high crystalline quality and c-axis orientation. The onset transition
temperature is up to 38 K with the zero resistivity temperature about 36.7 K.
Both the R-T and M-T data show a very sharp superconducting transition with
transition width 0.4 K. We also found that the samples possess very large
current carrying ability and high upper critical fields, indicating potential
applications requiring very high field. The above simple and safe one-step
technique of single crystal growth can be effective in other systems of
Fe-based superconductors.
