Magnetization process evaluation and tensile stress effect in direct magnetostriction measurement of amorphous microwires

VÁZQUEZ, MANUEL; MOYA, JAVIER A.

Minneapolis

Conferencia; Annual Conference on Magnetism and Magnetic Materials; 2022

Institute of Electrical and Electronics Engineers (IEEE)

Under applied magnetic field microwires increase/decrease length depending on the magnetostriction sign, where magnetostrictive elongation is due to magnetization rotational processes as described in classical magnetism books. In amorphous alloys, magnetostriction is usually evaluated making use of inverse magnetoelastic effects (e.g., SAMR), sometimes not fully reliable (e.g., for positive magnetostriction) [1].This study in magnetostrictive and non-magnetostrictive amorphous microwires introduces two original aspects: i) Direct magnetostrictive elongation measurements as a function of applied field and tensile stress; and ii) Re-interpretation of the magnetization mechanism by comparing magnetostrictive elongation and magnetization curve.A home-made setup with suitable induction/pickup coils, a system to apply stress and a high-accuracy LVDT position sensor was used to measure magnetization, M, and magnetostrictive elongation,l/l,[2] in two amorphous microwire families: i) In-water-quenched (145μm diameter) highly magnetostrictive FeSiB, and vanishing positive/negative magnetostriction (CoFe)SiB microwires; and ii) Glass-coated FeSiBC microwire (20 m diameter). Fig. 1 shows high-sensitivity (l/l=10-8) representative data of l/l vs. M/Mmax and H where applied stress increases/reduces the elongation for negative/positive magnetostriction. Quantitative information on the rotational magnetization for low/high field regions is obtained (note the magnetostrictive effect in Fig. 2 inset on DW motion in the tiny wire due to a helical magnetization). This method to properly quantify the magnetostrictive elongation allows for a new magnetization/magnetostrictive analysis as required in mechanical sensor devices.[1] C. Gómez-Polo and M. Vazquez, J. Magn. Magn. Mater. 118, 86 (1993); K. Chichay et al., J. Appl. Phys. 116, 173904 (2014).[2] J. Moya et al., J. Magn. Magn. Mater. 476, 248 (2019).