We have directly imaged the spin transfer torque induced distortion of domain walls in current carrying ferromagnetic wires. Domain walls ranging from vortex walls in wide (1 m) wires, to transverse walls in narrow (100 nm) wires were studied. Scanning electron microscopy with polarization analysis (SEMPA) images show the distortion of the pinned domain walls while under the influence of a steady state current. As the applied current increases, the domain walls are first elastically distorted, and then break free from random pinning sites along the wires. These distortions are initiated at much lower current densities than required for propagation and generally have a characteristic reproducible response independent of the domain wall pinning site.
Physical Review Letters
magnetic domain walls, magnetic structure, nanostructured materials, SEMPA, Spin Transfer Torque