Origin of relationship between ferromagnetic response and damage in stretched systems

Abstract

This article presents a study whose purpose is to elucidate the damage effects in thin films on their magnetic response. Co40Fe40B20 and Ni80Fe20 films of different nanometric thicknesses were stretched by more than 10% and in situ probed by atomic force microscopy measurements to determine their irreversible mechanical behavior (multi-cracking, buckling). Once these phenomena have been well identified, magnetic behavior of these stretched systems has been studied by ferromagnetic resonance to measure resulting magnetic anisotropy and damping evolutions. All of these experimental studies show that the magnetic properties are mainly affected by the stresses generated during the damage but not by the local discontinuities induced by the numerous cracks and buckles. This is in particular confirmed by the almost zero sensitivity to the damage of the magnetic properties of Ni80Fe20 alloy which is known for its vanishing magnetostriction.

Strain engineered domain structure and their relaxation in perpendicularly magnetized Co/Pt deposited on flexible polyimide

“…Merabtine et al have shown that the magnetic properties of a CoFeB film deposited on Kapton modified due to the high stress applied during the damage formation (cracking/buckling). But there is almost no effect of cracking or buckling on the magnetic properties of zero magnetostrictive alloy NiFe [37]. Hence we can conclude that the negligible effect of compression is not a result of structural modification of our film.…”

A System for Monitoring of Broadband FMR Phenomenon in Low-Carbon Steel Films Subjected to Deformations

“…Several factors influence the damping of FMR, having an internal and external character. The internal contributions are related to the properties of a given material [ 2 , 7 , 20 ] (i.e., the effect of eddy current damping), while the external ones are associated with defects in the sample [ 20 , 25 , 26 , 27 ]. In polycrystalline materials, the line broadening mechanism can be dominated by magnetocrystalline anisotropy (in conjunction with polycrystalline structure) [ 19 , 21 , 28 ].…”

“…In the context of the above-mentioned factors, the FMR absorption characteristic can provide information about the state of the material, as deformations in steels significantly affect changes in their structure and properties. Growing strains increase the number of defects in the lattice, which cause the broadening of the absorption line [ 25 , 28 ]. In the case of polycrystals, grain boundaries are an additional influencing element.…”

“…Deformation of the crystal lattice causes anisotropy, which also results in the appearance of directions of easy and hard magnetization axes in the material. Their distribution may also interchange depending on the stage of the deformation process [25]. Additionally, the deformation process itself in the steels strongly affects the properties in surface layers and further the resultant magnetic anisotropy characteristic [1,2,19,25,26].…”

“…Their distribution may also interchange depending on the stage of the deformation process [25]. Additionally, the deformation process itself in the steels strongly affects the properties in surface layers and further the resultant magnetic anisotropy characteristic [1,2,19,25,26]. Thus, although the testing depth for the FMR frequency range is limited by the skin depth effect, the method may be promising for the evaluation of material changes.…”