Modeling the differential susceptibility by Lorentzians.

Abstract

The idea of extracting information on magnetically different phases from magnetic measurements is very attractive, and many efforts have been made in this area. One of the most popular directions is to use the Preisach model formalism to analyze the 2D Preisach distribution function (PDF) obtained either from first order reversal curves or minor loops. Here, we present an alternative, a much simpler procedure-the analysis of the derivative of the saturation magnetization loop, the differential susceptibility curve. It follows the Lorentzian shape with very high accuracy for ferromagnetic polycrystalline materials. This allows decomposing any differential susceptibility curve of a complex multi-phase material into individual components representing different magnetic phases by Lorentzian peaks-in the same way as it is done in x-ray diffraction analysis of materials. We show that the minor differential susceptibility curves also have the Lorentzian shape that can facilitate the calculation of the Preisach distribution function from the experimental curves and reduce noise in the resulting PDF.