Permalloy nanostructures for magneto-impedance measurements

The magneto-impedance (MI) effect attracts an increasing interest due to its high value in comparison to magnetic resistance (MR) effects, opening possible applications as e.g., high-sensitivity magnetic field detectors, magnetic recording heads, etc. However, for most samples employed in MI measurements in the literature, i.e., amorphous wires, magnetic multilayers and ribbons, the real three-dimensional domain structure remains unknown. In order to find the relation between the magnetic domain structure and the respective value of the MI effect, permalloy (Ni₈₁Fe₁₉) nanowires and thin films were produced by electron-beam lithography (EBL), lift-off technique and focused ion beam (FIB) milling. Wires and other structures (rectangles, circles), and domain pinning sites (notches) were manufactured with optimized dimension (size, thickness, etc.). The magnetic structure of our samples and the MI effects were analyzed by magnetic force microscopy and transport measurements.