Simulated electric field applied by the AFM tip in 2, 10 and 40 nm films by COMSOL (point line), and the electric field due to the cone (Eq. 5) and the electric field expressed by Eq. 3 of previous works [10, 13, 14] (solid lines). The tip radius is 60 nm (tip \(\#\)1). (See Additional file 1.)
