Magnetoelasticity of $mathrm{Co_{25}}mathrm{Fe_{75}}$ thin films

We investigate the magnetoelastic properties of $mathrm{Co_{25}}mathrm{Fe_{75}}$ and $mathrm{Co_{10}}mathrm{Fe_{90}}$ 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 $lambda_{mathrm{Co_{25}}mathrm{Fe_{75}}}=(-20.68pm0.25)times10^{-6}$ and $lambda_{mathrm{Co_{10}}mathrm{Fe_{90}}}=(-9.80pm0.12)times10^{-6}$ at room temperature. In stark contrast to the positive magnetostriction previously found in bulk CoFe crystals. $mathrm{Co_{25}}mathrm{Fe_{75}}$ 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.