Size dependence of magnetic domain patterns in exchange-biased Permalloy/NiO microstructures

The magnetic domain structure in Permalloy (Ni81Fe19) micropatterns (10-100 m) on NiO has been investigated by means of soft x-ray photoemission electron microscopy. The exchange anisotropy between the Ni81Fe19 patterns and the NiO layer results in the formation of complex domain structures which markedly differ from the simple Landau-Lifshitz configurations. The domain structures reflect the competition between the exchange anisotropy and the dipole-dipole interaction in a weakly coupled system. The observed domain structures change with the feature size, as the domain patterns lose complexity in the smaller structures.