Alternating Gradient Force Magnetometer (AGFM), introduced by Flanders, is an integral method of magnetometry which determines the bulk magnetic moment of a sample by measuring the net translational force exerted on a magnetic dipole by a gradient magnetic field, . The applied magnetic field can be either parallel or perpendicular to the sample surface and the principle of the AGFM is sketched in figure 3.1.
In terms of capabilities, the applied field of the AGFM is studied continuously to identify and assess comparative benefits from other magnetometers. It is observed that in the AGFM, the amount of magnetic materials that are required for measuring it can be small. This is not the case with other measurement systems. Here the weaker magnetic samples can be measured at ease.
Usually quick connect transducer is provided that enables for better sample charging and for better control. Feedback servo signals are sometimes used in the field sweep and the static sweep. This increases the range of control, and finally, the resonance, the probe Q, phase and sensitivity are easily adjustable. This means that faster data collection for sample analysis is possible. This is done at 10 ms per data point. The maximum sample size is very flexible, as it can support till a 5 mm x 5 mm x 2 mm at times. This, however, will be dependent on the form of construction.
Now the original reasons for why the AGFM was selected and used more popularly are seen to be because of the need for better ambient temperature operations. Where sensitivity is very high for others, in the case of the AGFM better tolerance and sensitivity is aimed at. The operation could be extendable to cryogenic temperatures in the future. There are some constraints in the form of cost to consider, film sample thickness etc. As of current times, research studies show that the instrument is used in the context of study of exchange interactions between the hard (FePt) and soft (Fe) phase. Structural characterizations are studied using the instrument and the AGFM is useful for investigating morphology with atomic force microscopy.