Magnetic domain wall pinning by focused ion beam milling of permalloy layers

Permalloy thin films were deposited on SrTiO(3) Substrates by magnetron sputtering and patterned using a 30 kV Ga(+) focused ion beam to fabricate narrow bridges with notches pointing perpendicular to the bridge. These notches were used to introduce geometrical nanoconstructions in order to study the formation and pinning of magnetic domain walls. Notches were placed either along one side of the bridge or in opposite positions at both sides. Several milling conditions were tested to evaluate the patterning. Atomic and magnetic force microscopy were performed to study the effect of the introduced notches on the magnetization of the bridge. While a plain bridge shows no magnetic contrast, indicating a uniform magnetization, notched bridges clearly demonstrate that domain walls are pinned around the notches. (C) 2008 Elsevier B.V. All rights reserved.