  First-principles calculations and a tight-binding analysis predict that the
iron-pnictide BaCrFeAs2 is a promising candidate for half-metallic material
with fully-compensated magnetization. The transition-metal ions Cr and Fe
prefer the three-dimensional intervening lattice, which yields the
antiferromagnetic order of spin orientations. Due to the difference between Cr
and Fe in the electronegativity, a band gap is opened at the Fermi level in the
spin channel in which Fe provides the majority carriers. The selective
hybridization between 3d orbitals of Cr and As:4p states due to the peculiar
lattice structure of the iron-pnictide is shown to be crucial for the novel
properties.
