Magnetoelasticity of $\mathrm{C}{\mathrm{o}}_{25}\mathrm{F}{\mathrm{e}}_{75}$ thin films

Abstract

We investigate the magnetoelastic properties of $\mathrm{C}{\mathrm{o}}_{25}\mathrm{F}{\mathrm{e}}_{75}$ and $\mathrm{C}{\mathrm{o}}_{10}\mathrm{F}{\mathrm{e}}_{90}$ thin films by measuring the mechanical properties of a doubly clamped string resonator covered with multi-layer stacks containing these films. For the magnetostrictive constants we find ${\lambda }_{\mathrm{C}{\mathrm{o}}_{25}\mathrm{F}{\mathrm{e}}_{75}}=(-20.68\pm 0.25)\times 10^{-6}$ and ${\lambda }_{\mathrm{C}{\mathrm{o}}_{10}\mathrm{F}{\mathrm{e}}_{90}}=(-9.80\pm 0.12)\times 10^{-6}$ at room temperature. In stark contrast to the positive magnetostriction previously found in bulk CoFe crystals. $\mathrm{C}{\mathrm{o}}_{25}\mathrm{F}{\mathrm{e}}_{75}$ thin films unite low damping and sizable magnetostriction and are thus a prime candidate for micromechanical magnonic applications, such as sensors and hybrid phonon-magnon systems.

4 pages, 4 figures, SI