mK-ready Modules
Selected AFM Measurement Modes
Magnetic Force Microscopy (MFM)
MFM uses cantilevers with magnetic coatings which are
sensitive to magnetic interactions between tip and sample.
Like most MFMs, attoMFM applies an AC actuation of the
cantilever to achieve highest sensitivity. The cantilever
mechanically oscillates at its natural resonance frequency f 0
in an orientation where its magnetic moment is swinging
perpendicularly to the sample surface (z-direction).
Resonance frequency (as well as amplitude and phase)
of the cantilever is affected by the magnetic interaction.
This frequency shift Δf = f res - f 0 can be detected by classi-
cal lock-in techniques and is the most relevant physical
quantity to measure due to its direct proportionality to
the derivative of the local force F in the limit of small
oscillation amplitudes: ∂F z /∂z ~ 2 K Δ f /f 0 .
The measurement therefore yields a 2D map of actual local
magnetic stray field: ∂F z /∂z ~ m tip,z ∂H z /∂z (where m tip,z is
the magnetization of the tip perpendicular to the sample
surface) with very high spatial resolution. Using a phase-
locked loop (PLL) technique, resonance frequency shifts
as small as 1 μHz can be detected.
Cantilever
Dither
Sample