Domain configuration and magnetization switching in arrays of permalloy nanostripes

• A shape anisotropy-induced single domain remanent state is present in the stripes. Closure domains are formed under external fields.
• Separation distances between neighboring stripes (500 nm) are enough to overcome the magnetostatic coupling and avoid a multi-stripe character.
• Micromagnetic simulations predict critical distances of around 500 nm for the onset of magnetostatic coupling between neighboring elements.
• Simulations predict stripes with a small longitudinal separation to behave as single elements, with domain walls “jumping” between them.

The proximity effect in the collective behavior of arrays of magnetic nanostripes is currently a subject of intensive research. The imperative of reducing the size and distances between elements in order to achieve higher storage capacity, faster access to the information as well as low energy consumption, brings consequences about the isolated behavior of the elements and devices. Parallel to each other permalloy nanostripes with high aspect ratio have been prepared by the nanolithography technique. The evolution of the closure domains and the magnetization direction in individual nanostructures has been imaged under applied magnetic fields using Variable Field Magnetic Force Microscopy. Moreover, the magnetostatic interactions between neighboring elements and the proximity effects in arrays of such nanostructures have been quantitatively analyzed by Magnetic Force Microscopy and micromagnetic simulations. The agreement between simulations and the experimental results allows us to conclude the relevance of those interactions depending on the geometry characteristics. In particular, results suggest that the magnetostatic coupling between adjacent nanostripes vanishes for separation distances higher than 500 nm.