Interacting tails of asymmetric domain walls: Theory and experiments

In this paper, we address the structure and interaction of neighboring asymmetric N\'eel and Bloch walls in soft ferromagnetic films. First, we review a recent reduced model for the structure of parallel systems of asymmetric walls with potentially interacting tails and provide a derivation via the method of matched asymptotic expansions, starting from the micromagnetic-torque equation. Then, we report on experimentally observed domain-wall transitions under a varying hard-axis field in ${\mathrm{Co}}_{40}{\mathrm{Fe}}_{40}{\mathrm{B}}_{20}$ films. Upon the wall transition, the average hard-axis magnetization in the domains increases significantly, by an amount that depends on the width of the domains. For films of moderate thickness, the hard-axis magnetization jump that the theory predicts excellently agrees with the experimental data. Hence, we conclude that interacting tails of neighboring asymmetric N\'eel walls cause the observed additional rotation of the magnetization towards large hard-axis fields.