Presentation Information
[P1-55]Measuring initial curves and minor hysteresis loops for rare earth magnets using the Pulsed Field Magnetometer (PFM) system
*Robin Cornelius1, Jack Wade1, Stuart Harwin1, James Mckenzie1 (1. Hirst Magnetic Instruments Ltd (UK))
Keywords:
Pulsed Field Magnetometer,BH Loop - initial curves and minor loops,SmCo,NdFeB,FORC diagrams
This presentation will review recent progress and results gained from the Hirst generation 8 Pulsed Field Magnetometers on initial magnetisation curves, minor loops being applied to samples and the implementation of First Order Reversal Curves (FORCs) on a PFM. The initial curve represents the initial magnetization process of a permanent magnet from when it is completely unmagnetized. This curve is important for understanding the composition, metallurgy, and microstructure of a material. We will present results for NdFeB and SmCo magnets. Minor Loops are generated when the applied magnetic field is reversed but does not reach the saturation point, creating smaller loops within the main hysteresis loop. This provides information about the reversibility of magnetization within a specific field range and can be used to analyse the stability of a permanent magnet under changing magnetic fields. We will present results for NdFeB magnets. First order reversal curve (FORC) measurements provide insight into the magnetic properties of materials, information that is not possible to obtain from a full hysteresis loop alone or individual minor loops. FORC curves help in identifying the distribution of switching and interaction fields, and in distinguishing between multiple magnetic phases in composite or hybrid materials containing more than one phase of magnetic materials. This information can be used to analyse magnet production techniques and novel materials. We will present results for NdFeB magnets. This new option on the latest generation 8 PFMs from Hirst and takes advantage of the full pulsed field that drives the sample through all four quadrants of the hysteresis loop during a measurement.
