Magnetic domain and domain-wall imaging of submicron Co dots by probing the magnetostrictive response using atomic force microscopy

An approach to image the domains and domain walls of small ferromagnetic en tities using atomic force microscopy (AFM), with a nonmagnetic AFM probe, h as been developed. Exciting the sample in an external ac magnetic field, th e distribution of magnetostrictive response at the surface is detected. By this technique, the domains and domain walls of submicron Co dots have been imaged with a 1 nm lateral resolution. In elliptical Co dots with a 350-nm -long axis on a triangular lattice array with 400 nm periodicity, we find e vidence for two domains with opposite magnetization orientation across a wa ll. The domain-wall width in these dots is found to be about 35 nm. Further more, we observe a ferromagnetic alignment of the domains in the neighborin g dots, which suggests a magnetostatic interaction among the dots. (C) 2000 American Institute of Physics. [S0003-6951(00)02020-9].