Magnetic studies in octagon-patterned permalloy submicro-wires

Octagon-patterned permalloy submicron wires composed with fixed octagon-shape elements in different configurations were fabricated by an electron-beam lithography process. In the longitudinal magnetic field both magnetic switch field and the variation of the magnetoresistance ratio near the magnetic switch field increase with an increasing number of octagons perpendicular to the wire direction, and also decrease with increasing temperature from 10 to 300 K. At the remanent state, we have observed a single domain in each parallel octagon unit and vortex domains in all the perpendicular units.