Magnetic Force Microscopy
Advanced MFM Operation
Rev. D
Dimension 3100 Manual
265
Figure 15.3a
High-resolution Magnetic Force Gradient Image
15.3.2 Fine Tuning Interleave Controls
Certain scanning parameters found under
Interleave Controls
can be set to values in the Interleave
(Lift) scan that differ from the values in the main scan. These parameters are enabled by clicking on
the circular flag to the immediate left of the desired Interleave control, toggling its state from
Off
(gray bullet) to
On
(green bullet). When the flag is set to
Off
, the main scan control parameter
setting takes precedence. When the flag is set to
On
the displayed Interleave scan value is active,
overriding the main scan value.
15.3.3 Drive Amplitude
For MFM, of particular use is the Interleave
Drive Amplitude
. This parameter can affect a
magnetic force image in a variety of ways.
•
Increasing the
Drive Amplitude
can improve the signal-to-noise ratio when using phase
detection or frequency modulation. This is because intrinsic, low-level noise interferes
less when measuring the phase of a larger cantilever oscillation amplitude and hence
stronger photodetector output. As an illustration, try setting the Interleave
Drive
Amplitude
to
0
; the resulting phase image will be pure noise because one cannot
measure the phase of a non-oscillating cantilever.
•
In
LiftMode
, the Interleave
Drive Amplitude
can often be set to a value larger than in
the main scan, thus giving optimal signal-to-noise. In some cases this is beneficial as
long as the
Drive Amplitude
is not increased to the extent that the tip strikes the surface
on the low point of its swing. The signatures of tip-sample contact are white and black
spots in the image, or, in extreme cases, noisy, high-contrast streaks across the whole
Summary of Contents for Dimension 3100
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