The authors investigate the magnetization reversal process of a new structure ferromagnetic submicron dot composed of lateral gradient magnetization by micromagnetic simulation. The reversal process in this structure initiates at both edges along and perpendicular to the applied magnetic field due to introducing demagnetizing field from the interface of gradient magnetization. It leads to the two-stage nucleation process in the structures. Based on numerical analysis, a submicron dot with quarter lateral gradient magnetization is proposed to control the chilarity of a vortex, which is important for the application using the vortex's chilarity

In-plane alternating pulses of current applied with an external magnetic field that changes the strength and direction of the exchange bias are observed in NiFe/Cu/NiFe/FeMn spin valves. To provide clear evidence of this spin-polarized current for antiferromagnets incorporated in spin valves, a series of measurements was carried out to rule out the influence of Joule heating caused by the pulse. The measurements revealed that Joule heating plays a minor role in the impact of exchange bias, thus providing more convincing evidence of the spin torque exerted on the interfacial antiferromagnetic moments.

CoFe2O4 films of 100 nm thickness were deposited on 20 nm, rf magnetron-sputtered Fe3O4 underlayers on naturally oxidized Si (100) substrates. These films were then annealed, and the magnetic properties and microstructures were investigated as a function of annealing temperature. Results show that the optimum annealing temperature to obtain the maximum coercivity decreases from 700℃ for films without Fe3O4 underlayers to 500℃ for films with underlayers. The decreased annealing temperature corresponds to a phase transformation of the Fe3O4 underlayers at about 400-500℃, which accelerates the increase in grain size of the cobalt ferrite films.

A simplified way, which combines nanosphere lithography with sputtering technology, to fabricate oxide antidot arrays is reported. Using the resputtering effect of oxygen negative ions during sputtering deposition in oxygen environment, CoFe2O4 antidot arrays are fabricated directly on a wafer masked by latex spheres, which is self-assembled by nanosphere lithography. The result shows that the coercivity of the CoFe2O4 antidot arrays increases substantially due to the pinning of domain walls in the vicinity of antidots. This fabrication method can be extended in the fabrication of other oxide antidot arrays.