
The force exerted on a dipole is the dot product of the dipole moment and the gradient of the field at the surface. In magnetic force microscopy-- MFM-- these dipole magnetic forces are detected as a change in cantilever phase and amplitude a finite distance above the surface. In an MFM image, the tip is tapped on the surface to measure the surface morphology, and then re-scanned across the surface 50-150 nm above the surface to measure magnetic contrast. This re-scan above the surface is done in what is called lift mode. MFM in lift mode is just one of many interleave scans that can be performed-- a scan across the surface between morphology scans.
The left image shows the morphology of a computer hard-drive. Visible are highly oriented surface scratches. The right image shows MFM magnetic contrast in the tapping amplitude using a 100 nm lift distance with a magnetized Veeco MESP MFM probe.
No comments:
Post a Comment