Multicracking and Magnetic Behavior of Ni₈₀Fe₂₀ Nanowires Deposited onto a Polymer Substrate

Abstract

This work presents the effect of large strains (up to 20%) on the behavior of magnetic nanowires (Ni80Fe20) deposited on a Kapton substrate. The multicracking phenomenon was followed by in situ tensile tests combined with atomic force microscopy measurements. These measurements show, on the one hand, a delay in crack initiation relative to the nonpatterned thin film and, on the other hand, a saturation of the length of the nanowire fragments. The latter makes it possible to retain the initial magnetic anisotropy measured after deformation by ferromagnetic resonance. In addition, the ferromagnetic resonance line profile (intensity, width) is minimally affected by the numerous cracks, which is explained by the small variation in magnetic anistropy and the low magnetostriction coefficient of Ni80Fe20.