Controllable strain-induced uniaxial anisotropy of Fe₈₁Ga ₁₉ films deposited on flexible bowed-substrates

We propose a convenient method to induce a uniaxial anisotropy in magnetostrictive Fe₈₁Ga₁₉ films grown on flexible polyethylene terephthalate (PET) substrates by bending the substrate prior to deposition. A tensile/compressive stress is induced in the Fe ₈₁Ga₁₉ films when PET substrates are shaped from concave/convex to flat after deposition. The stressed Fe₈₁Ga ₁₉ films exhibit a significant uniaxial magnetic anisotropy due to the internal stress arising from changes in shape of PET substrates. The easy axis is along the tensile stress direction and the coercive field along easy axis is increased with increasing the internal tensile stress. The remanence of hard axis is decreased with increasing the compressive stress, while the coercive field is almost unchanged. A modified Stoner-Wohlfarth model with considering the distribution of easy axes in polycrystalline films is used to account for the magnetic properties tuned by the strain-controlled magnetoelastic anisotropy in flexible Fe₈₁Ga₁₉ films. Our investigations provide a convenient way to induce uniaxial magnetic anisotropy, which is particularly important for fabricating flexible magnetoelectronic devices.