Design of a Magnetic Force Microscope for Imaging
Nanoscale Vortex Motion
have many potential uses, including generation of large magnetic fields and
minute sensor arrays for medical diagnostics. These applications are presently
limited by the uncontrolled motion of ‘vortices’: swirling cur-rents
that contain mag-netic fields within the superconductor. On the other hand,
controlled vortex motion presents new opportunities for computing.
Given these challenges and opportunities, it is imperative to gain a better
understanding of the dynamics of single vortices. We have therefore designed
a new cryogenic magnetic force microscope to detect and measure magnetic
forces with 10 nanometer spatial resolution and sub-pico Newton force resolution.
The drawing shows the instrument design, with a blow-up of the sample imaging
region. The sample sits face-up on the white surface, while a magnetic-tipped
cantilever (shown in yellow, just above the sample) is used to measure magnetic
forces and to manipulate vortices. The magnetic force results in a deflection
of the cantilever, which is measured via a laser beam reflected off the cantilever
from behind (the small blue circle). The unique feature of this new imaging
tool is the vertical cantilever, which allows direct detection of magnetic
forces in the plane of the sample.