High-resolution MFM: simulation of tip sharpening

The transfer functions of tips with various sharpened tip ends were calculated and the resolution of these tips was esti-mated by considering the resolution limit due to thermal noise at room temperature. The tip having an ellipsoidal tip end (ellipsoidal tip) is found to be a suitable candidate for high-resolution magnetic force microscopy. Sharpening of the flat tip end makes zero signal frequencies disappear for tips with ellipticities larger than tan 45 . The sensitivity shows a maximum around an ellipticity of tan 80 . The ellipsoidal tip shows a much smaller tip thickness dependence compared to the tip having a flat tip end because only the tip end mainly contributes to signals in case of the ellipsoidal tip