  Magnetic axis rotation (MAR) in ferromagnetic (FM) layers is crucial for
strain-mediated converse magnetoelectric coupling. Employing the density
functional theory (DFT), we computationally study the magnetic anisotropy of
selected deformed FM materials such as body-centered iron. The results show
that the short axis is more energy-favorable at high in-plane strain difference
than previously predicted phenomenologically. This anomalous trend and the
complex energy behaviors at different strain conditions explain why
spin-lattice dynamics (SLD) simulation does not produce in-plane MAR and imply
couplings between different energy terms together with high order coefficient
contributions.
