AGM
Princeton Micromag/Lakeshore Cryotronics 2900 Series Alternating Gradient Magnetometer
PRIMARY USE
Material characterization and identification
The magnetic properties of a material depend on much more than just the elemental composition. Very similar materials, like the iron oxides that make up ochres, can still look quite different due to their magnetic properties.
SIMPLE STATS
Sample Size: 5x5x2mm, 0.1 - 200.0mg
Sensitivity (1 s Average): 10 nemu / 1e-9 Am^2/kg
Maximum Field: 1 T / 10,000 Oe
Two measuring positions for anistropic samples
PRIMARY MEASUREMENTS
Hysteresis Loop
Backfield Curve
FORC, First Order Reversal Curve
PRIMARY MEASUREMENTS
Hysteresis is the ability of ferromagnetic materials to "remember" an applied field. Hysteresis loops record this "memory" by measuring the magnetic field induced in a sample when that sample is exposed to a changing magnetic field (left). The field starts at maximum, reduces to zero, increases to maximum in the opposite (negative) direction, then reverses until it gets back where it started. The gap in this loop represents the "memory". This, combined with a similar measurement called a backfield curve, allows us to identify the magnetic mineralogy of the material. FORCs are a modern version of these that offers a more sophisticated look at magnetic behavior.