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Magnetic Force Microscopy with the Nano-RT

Procedure

  1. Magnetize the MFMR Tip by placing the permanent magnet in close proximity (mm)
  2. Insert MFMR cantilever and sample into standard positions (the magnetic tip holder and sample holder will not significantly affect the image quality)
  3. Choose close-contact imaging mode
  4. Find the resonant frequency of the cantilever
  5. Reduce the maximum amplitude of the resonant peak to less than 1.5 V
  6. Collect a topography image of the area of interest
  7. To collect an MFM image you will need to raise the tip above the surface of the sample to remove the topography component. The simplest way is to change the set point by increasing the absolute magnitude of the cantilever oscillation.
  8. Start collecting an image while slowly increasing the cantilever set point. You will notice the topographic image becoming less sharp until no information is evident.
  9. As the topographic image fades away, you should be able to clearly see the magnetic information on a surface by looking at the phase signal.
  10. As complex as this seems, We were able to collect MFM images of hard disks within 30 minutes of imaging:
Example Figure 1: Magnetic domains on a 5 Gb hard disk: A) Topographic image in close contact mode; B) Phase image after increasing the set point of the same area in A. Both images are 40x40 µm2.
Figure 2: 5x5 µm MFM images of a 5 Gb hard disk (A) and a 70 Gb hard disk (B). The magnetic domains in A are ~ 12 µm in length while the domains in B are on the order of 250 nm. This shows the high resolution capability of the Nano-RT with MFM.
Figure 3: 10x10 µm MFM images of magnetic tape, topography (A) and phase image (B). The magnetic domains are ~ 650 nm in length. Image courtesy of Toyo Corp.

 
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