Modulated Helical Metals at Magnetic Domain Walls of Pyrochlore Iridium Oxides

Spontaneous symmetry breakings, metal-insulator transitions, and transport properties of magnetic-domain-wall states in pyrochlore iridium oxides are studied by employing a symmetry adapted effective hamiltonian with a slab perpendicular to the (111) direction of the pyrochlore lattice. Emergent metallic domain wall, which has unconventional topological nature with a controllable and mobile metallic layer, is shown to host Fermi surfaces with modulated helical spin textures resembling Rashba metals. The helical nature of the domain-wall Fermi surfaces is experimentally detectable by anomalous Hall conductivity, circular dichroism, and optical Hall conductivity under external magnetic fields. Possible applications of the domain-wall metals to spin-current generation and "half-metallic" conduction are also discussed.