Off-axis electron holography of exchange-biased CoFe/FeMn patterned nanostructures

Off-axis electron holography and micromagnetic simulations have been used to investigate magnetization reversal mechanisms and remanent states in exchange-biased submicron Co₈₄Fe₁₆/Fe₅₄Mn₄₆ patterned elements. Domain structures within the elements were characterized despite the narrow thickness (∼3 nm) of the ferromagnetic layer relative to the total element thickness (∼42 nm). Individual elements were able to support different remanent states and their magnetic microstructure was sensitive to their size. The simulations confirmed that the coercivities of the elements and their domain structures were highly sensitive to the strength and orientation of the pinning field. A good fit to the experimental data was provided by using an interface exchange field that had a fixed amplitude and direction in the simulations, and small disagreements were attributed to structural imperfections. These differences emphasize the value of an experimental technique such as electron holography for probing local micromagnetic structure in individual nanostructured elements.