Epitaxial growth and electric control of magnetic behaviors in exchange biased IrMn/FeGa/MgO/PMN-PT heterostructures

We grew exchange biased (001)-textured IrMn/epitaxial FeGa bilayers on ferroelectric PMN-PT(001) substrate with assistance of an MgO buffer layer and investigated the electric control of magnetic behaviors. The as-grown sample exhibits square, asymmetrically shaped, and two-step loops at different magnetic field orientations due to the combined effect of the intrinsic magnetocrystalline anisotropy and the collinear uniaxial and unidirectional magnetic anisotropies, which can be interpreted by the magnetization reversal of domain wall nucleation. After polarized by an electric field, another kind of asymmetrically shape loops with three steps in the descending and two steps in the ascending branch is additionally observed because the uniaxial magnetic anisotropy is greatly enhanced and becomes perpendicular to the exchange bias. The angular dependent magnetic behavior suggests the exchange bias is slightly rotated by the electrically induced strain. The electric field dependence of coercive field and uniaxial magnetic anisotropy exhibit an asymmetrical butterfly-like shape, indicating a strain-mediated magnetoelectric coupling with a net 109 degrees polarization switching of PMN-PT.

Automated summary

In this study, exchange biased (001)-textured IrMn/epitaxial FeGa bilayers were grown on a ferroelectric PMN-PT(001) substrate with the assistance of an MgO buffer layer. The electric control of magnetic behaviors was investigated. It was found that the combined effect of intrinsic magnetocrystalline anisotropy and collinear uniaxial and unidirectional magnetic anisotropies resulted in square, asymmetrically shaped, and two-step loops at different magnetic field orientations. After being polarized by an electric field, asymmetrically shaped loops with three steps in the descending and two steps in the ascending branch were additionally observed, indicating enhanced uniaxial magnetic anisotropy perpendicular to the exchange bias. The angular dependent magnetic behavior suggested a slight rotation of the exchange bias by electrically induced strain. The electric field dependence of coercive field and uniaxial magnetic anisotropy exhibited an asymmetrical butterfly-like shape, indicating a strain-mediated magnetoelectric coupling with a net 109 degrees polarization switching of PMN-PT.