Domain configurations in Co/Pd and L10-FePt nanowire arrays with perpendicular magnetic anisotropy

TL;DR

This study fabricates and analyzes Co/Pd and L10-FePt nanowire arrays with perpendicular magnetic anisotropy, revealing how magnetostatic interactions influence domain configurations and reversal processes, providing insights into domain wall behavior in nanoscale magnetic systems.

Contribution

It introduces a fabrication method for nanowire arrays with perpendicular magnetic anisotropy and investigates their magnetic domain configurations and reversal mechanisms.

Findings

Alternating magnetization states observed in ~75% of Co/Pd wires after demagnetization.

Weaker magnetic interactions in FePt lead to less prevalent alternating states.

Domain reversal involves nucleation and propagation of reverse domains along nanowires.

Abstract

Perpendicular magnetic anisotropy [Co/Pd]15 and L10-FePt nanowire arrays of period 63 nm with linewidths 38 nm and 27 nm and film thickness 27 nm and 20 nm respectively were fabricated using a self-assembled PS-b-PDMS diblock copolymer film as a lithographic mask. The wires are predicted to support Neel walls in the Co/Pd and Bloch walls in the FePt. Magnetostatic interactions from nearest neighbor nanowires promote a ground state configuration consisting of alternating up and down magnetization in adjacent wires. This was observed over ~75% of the Co/Pd wires after ac-demagnetization but was less prevalent in the FePt because the ratio of interaction field to switching field was much smaller. Interactions also led to correlations in the domain wall positions in adjacent Co/Pd nanowires. The reversal process was characterized by nucleation of reverse domains, followed at higher fields by propagation of the domains along the nanowires. These narrow wires provide model system for exploring domain wall structure and dynamics in perpendicular anisotropy systems.