  We present a comprehensive comparison of the infrared charge response of two
systems, characteristic of classes of the 122 pnictide (SrFe2As2) and 11
chalcogenide (Fe_1.087Te) Fe compounds with magnetically-ordered ground states.
In the 122 system, the magnetic phase shows a decreased plasma frequency and
scattering, and associated appearance of strong mid-infrared features. The 11
system, with a different magnetic ordering pattern, also shows decreased
scattering, but an increase in the plasma frequency, while no clear
mid-infrared features appear below the ordering temperature. We suggest how
this marked contrast can be understood in terms of the diverse magnetic
ordering patterns of the ground state, and conclude that while the high
temperature phases of these systems are similar, the magnetic ordering strongly
affects the charge dynamical response. In addition, we propose an optical
absorption mechanism which appears to be consistent with information gained
from several different experiments.
