  Using density functional theory and LDA+U method, we investigate magnetic and
electronic structure of Y$_{2}$Ir$_{2}$O$_{7}$ and rare-earth based pyrochlore
iridates. Our study reveals that the ground state is a non-collinear magnetic
insulating state. Due to strong spin-orbit coupling in Ir 5\textit{d}, there is
an unusual correlation between the bands near Fermi level and the magnetization
direction, resulting in a possibility of insulator-to-metal transition under
applied magnetic field. This makes pyrochlore iridates a good candidate for
possible magnetoressitance and magnetooptical applications.
