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The switching of submicrometer ferromagnetic wire junctions is investigated by controlled injection of domain walls (DWs). A three-terminal continuous [Ni.sub.80][Fe.sub.20] structure is described, consisting of two input wires and one output wire. Separate structures were fabricated by focused ion beam (FIB) milling, to inject either zero, one, or two DWs to the junction inputs. Introduction of DWs to the junction was performed using one or two DW injection pads with low switching fields. Hysteresis loops measured by magnetooptical Kerr effect (MOKE) magnetometry on the device output wires showed the coercivity of the output is strongly dependent on the number of DWs incident at the junction. By injecting either one or two DWs into the junction, it is possible to switch the output wire at two distinct field values, each markedly lower than the nucleation field of the junction. Results presented are relevant to the future development of spintronics DW logic systems, and for fundamental studies into DW resistance and interaction between DWs and wire morphology. Index Terms--Domain walls (DWs), focused ion beam (FIB), magnetic wires, magnetization reversal.

Experimental results of domain wall propagation velocity as a function of applied field in a 200-nm-wide permalloy nanostructure are presented. The structure was fabricated by focused-ion beam milling and designed to separate the domain wall nucleation from propagation. The measured velocities are very high, up to 1500 m/s at 49 Oe and the field dependence of the velocity is interpreted in terms of thermally activated wall motion through a series of pinning sites and a wall geometry that changes as a function of field. Index Terms--Domain walls, magnetic nanostructure, permalloy, thermal activation.

The controlled pinning and depinning of head-to-head domain walls with individual artificial nanotraps in rounded L-shaped Ni81Fe19 wires is discussed. Domain walls can be effectively pinned by domain wall nanotraps with dimensions of depth Dt=35nm and width Wt=55nm.

We report on the controlled pinning and depinning of head-to-head domain walls with individual artificial nanotraps in rounded L-shaped Ni81Fe19 wires. Domain walls were nucleated and injected into one arm of an L-shaped planar wire structure with a wire width of 200 nm and a thickness of 5 nm. The domain walls were propagated through a rounded corner into an orthogonal output wire by a 27 Hz anticlockwise rotating field. A highly sensitive magneto-optical Kerr magnetometer system was used to detect magnetization reversals around single wedge shaped nanotraps in the output wire of different samples. Domain wall propagation occurred at a mean measured x-field value of 6.8 Oe in the output wire arm when not interacting with a trap. Domain wall nanotraps with dimensions as small as depth Dt=35 nm and width Wt=55 nm were found to effectively pin domain walls. In general, the depinning field of a domain wall from a trap increased with trap size. Hysteresis loops and plots of domain walls depinning fields as a function of trap depth are presented. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]