Magnetic force microscopy (MFM) is a variety of atomic force microscopy, in which a sharp magnetized tip scans a magnetic sample; the tip-sample magnetic interactions are detected and used to reconstruct the magnetic structure of the sample surface. Many kinds of magnetic interactions are measured by MFM, including magnetic dipole–dipole interaction. MFM scanning often uses non-contact atomic force microscopy (NC-AFM) and is considered to be non-destructive with respect to the test sample. In MFM, the test sample(s) do not need to be electrically conductive to be imaged.

In MFM measurements, the magnetic force between the test sample and the tip can be expressed as

where ${\displaystyle {\vec {m}}\,\!}$ is the magnetic moment of the tip (approximated as a point dipole), ${\displaystyle {\vec {H}}\,\!}$ is the magnetic stray field from the sample surface, and μ₀ is the magnetic permeability of free space.

Because the stray magnetic field from the sample can affect the magnetic state of the tip, and vice versa, interpretation of the MFM measurement is not straightforward. For instance, the geometry of the tip magnetization must be known for quantitative analysis.

Typical resolution of 30 nm can be achieved, although resolutions as low as 10 to 20 nm are attainable.

A boost in the interest to MFM resulted from the following inventions:

Scanning tunneling microscope (STM) 1982, Tunneling current between the tip and sample is used as the signal. Both the tip and sample must be electrically conductive.

Atomic force microscopy (AFM) 1986, forces (atomic/electrostatic) between the tip and sample are sensed from the deflections of a flexible lever (cantilever). The cantilever tip flies above the sample with a typical distance of tens of nanometers.