Effect of mechanical strain on magnetic properties of flexible exchange biased FeGa/IrMn heterostructures

We have fabricated flexible exchange biased heterostructures with magnetostrictive Fe₈₁Ga₁₉ alloy as the ferromagnetic layer and Ir₂₀Mn₈₀ as the antiferromagnetic layer on polyethylene terephthalate substrates. The mechanical strain can modify both the strength and the orientation of the uniaxial anisotropy, giving rise to the switching between the easy and hard magnetization directions. Different from the previously reported works on rigid exchange biased systems, a drastic decrease in exchange bias field was observed under a compressive strain with magnetic field parallel to the pinning direction, but only a slightly decrease was shown under a tensile strain. Based on a Stoner-Wohlfarth model calculation, we suggested that the distributions of both ferromagnetic and antiferromagnetic anisotropies be the key to induce the mechanically tunable exchange bias.