  Recent experimental studies have revealed several unexpected properties of
Mn-doped BaFe2As2. These include extension of the stripe-like magnetic (pi,0)
phase to high temperatures above a critical Mn concentration only, the presence
of diffusive and weakly temperature dependent magnetic (pi,pi) checkerboard
scattering, and an apparent absent structural distortion from tetragonal to
orthorhombic. Here, we study the effects of magnetic impurities both below and
above the N\'eel transition temperature within a real-space five-band model
appropriate to the iron pnictides. We show how these experimental findings can
be explained by a cooperative behavior of the magnetic impurities and the
conduction electrons mediating the Ruderman-Kittel-Kasuya-Yosida (RKKY)
interactions between them.
