Separation of Topographic Features from Magnetic Force Images using Capacitive Coupling Effect
Tuesday, October 21, 2008, 2:40 pm, Room 206
Separation of topographic features from magnetic images has been an issue for the last 20 years in magnetic force microscopy (MFM). Although MFM is one of the most important imaging tools of nanoscale magnetic structures, this issue still remains largely unsolved and thus has limited the current capability of the MFM as a quantitative magnetic imaging tool. The frequent pickups of the topographic features are interpreted as transitions of the tip between bi-stable states of the tip-sample assembly in the noncontact and tapping regions in the conventional amplitude modulation MFM. The bi-stability originates from the long-range amplitude decrease due to the dc bias voltage for the uniform feedback polarity. As a method to make the amplitude increase in the noncontact region as the tip approaches the surface, an electrostatic force modulation method is introduced to utilize the capacitive coupling effect for magnetic imaging. MFM using electrostatic force modulation demonstrates the separation of the topographic features from the magnetic images with an enhanced stability. The stability is attributed to the different modulation method and servoing mechanism.