The Alternating Gradient Force Magnetometer (AGFM) and its components and working are the focus of this subtopic. The Alternating gradient force magnetometer was initially, introduced by Flanders. It is currently an integral method of magnetometry which determines the bulk magnetic moment of a sample. The AGFM does this by measuring the net translational force that is exerted on a magnetic dipole by a gradient magnetic field, . The gradient magnetic field is one where the field would change in its strength with respect to a given direction. This is more of a smaller linear magnetic field and is superimposed on larger magnetic fields.
On the other hand, in the case of the AGFM, 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. The main components present in the AGFM are the gradient field coil, the elastic suspensions, the Piezo sensor and the sample that is to be assessed.
Alternate Gradient Force magnetometer, the AGFM is a force instrument and it has three main parts. Firstly, the instrument has the capability to apply magnetic field to the sample at hand. The gradient field coils help achieve this. The sample will be located in between these coils. The magnetic field is a known magnetic field meaning it is not a random field of a random value. In this, the instrument could have different generating strengths. Different generational strengths as per the need of the use and the assessment required would be used. Much of the methods of generation have come into generation because of Flanders who was seen to create different coil combinations. An alternating field that was used with the gradient perpendicular resulted in a situation where a resonant extension was created.
The resonant extension in magnetic field generation is significant and the use of the AGFM ensured that the resonant element remains at room temperature. The piezoelectric bimorph is at room temperature here. The sample temperature can be varied here, and it is usually varied anywhere between 77 and 900 K. This form of variation possibly on the sample holds the advantage of a non-necessity of a nulling coil. The null flux coils are used for realizing the induced lift with very little drag. The null effect induced would be able to vertically center the magnets in the coils. In the past, magnetic field generation was constrained based on nulling coils. In the use of the AGFM there is no such constraint. Similarly, excessive frequency tracking is usually done with experiments. Excessive frequency tracking was needed for ensuring there was some form of an efficiency improvement in the assessment.