  We demonstrate a canted magnetization of biatomic zigzag Co chains grown on
the 5 x 1 reconstructed Ir(001) surface using density functional theory
calculations and spin-polarized scanning tunneling microscopy (SP-STM)
experiments. Biatomic Co chains grow in three different structural
configurations and are all in a ferromagnetic state. Two chain types possess
high symmetry due to two equivalent atomic strands and an easy magnetization
direction which is along one of the principal crystallographic axes. The easy
magnetization axis of the zigzag Co chains is canted away from the surface
normal by an angle of 33 degrees. This giant effect is caused by the broken
chain symmetry on the substrate in combination with the strong spin-orbit
coupling of Ir. SP-STM measurements confirm stable ferromagnetic order of the
zigzag chains with a canted magnetization.
