Six-fold configurational anisotropy and magnetic reversal in nanoscale Permalloy triangles

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 12-pointed switching astroid was measured using magneto-optical experiments and well reproduced numerically. Switching fields in different polar sectors were shown to reflect the different possible energy paths dictated by the configurational anisotropy during a 180° reversal of the magnetization, thereby giving a comprehensive view of the switching mechanism in these structures. A detailed analysis moreover highlighted the necessity to include the physical rounding of the structures in the simulations to account for the instability of the Y state.