The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of (Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect (MOKE). A transient MOKE signal followed by low amplitude oscillations was evidenced, with a s
trong dependence on applied magnetic field, temperature and ps-ASP amplitude. Careful interferometric measurement of the layers thickness variation induced by the ps-ASP allowed us to model very accurately the resulting signal, and interpret it as the strain modulated reflectivity (differing for $sigma_{pm}$ probe polarizations), independently from dynamic magnetization effects.
Six-fold configurational anisotropy was studied in Permalloy triangles, in which the shape symmetry order yields two energetically non-degenerate micromagnetic configurations of the spins, the so-called Y and buckle states. A twelve pointed switching
astroid was measured using magneto-optical experiments and successfully reproduced numerically, with different polar quadrants identified as specific magnetic transitions, thereby giving a comprehensive view of the magnetic reversal in these structures. A detailed analysis highlighted the necessity to include the physical rounding of the structures in the simulations to account for the instability of the Y state.
