Influence of Thermal Deformation on Exchange Bias in FeGa/IrMn Bilayers Grown on Flexible Polyvinylidene Fluoride Membranes

We investigated the influence of thermal deformation on the magnetic properties of flexible FeGa/IrMn exchange-biased (EB) bilayers grown on polyvinylidene fluoride (PVDF) membranes with the pinning direction parallel to the thermal deformation directions α₃₁ and α₃₂ of PVDF. Because with increasing temperature, the uniaxial anisotropy is reoriented from the α₃₂ to α₃₁ directions by the thermally induced compressive strain along the α₃₂ direction, both the coercive field H_c and the loop squareness M_r/M_s of FeGa/IrMn bilayers display a complex temperature-dependent behavior. The EB field H_c decreases with increasing temperature. A modified Stoner-Wohlfarth model was employed to account for the temperature dependence of magnetic properties in the flexible FeGa/IrMn bilayers.