Fig.1 Highly ordered Co antidot arrays with pore diameter about 1.3 μm a, 6.2 μm b, c magnification of a displaying mean hole dimension and the angle-to-angle distances

Fig.2 a AFM image of Co antidot arrays with pore diameter about 1.3 μm, b the same image was converted into a three-dimensional perspective

Fig. 3 XRD pattern of the continuous Co film

Fig. 4 Hysteresis hoops of the Co antidot arrays with pore diameter about 1.3 μm. The H‖ represents the direction of magnetic field applied parallel to the surface of Co antidot arrays and the H ⊥ perpendicular to Co antidot arrays

Fig. 5 Change of the coercivity (H) and squareness (M r/M s) at H‖ orientation with the pore diameter

Fig. 6 Hysteresis hoops of the Co films at H‖ orientation

Fig. 7 Structure model of Co 2D antidot arrays with hexagonal holes, where d is defined as the diameter of the corresponding PS particles, r is the radius of the hexagonal macropore, and a is the interhole distance