Low field frequency dependent magnetic susceptibility inversion

Abstract In this work we present an open source implementation of the procedure proposed by Ustra et al. (2018) to invert frequency dependent susceptibility (FDS) data to obtain quantitative information on grain-size variations of magnetic particles in the transition of superparamagnetic (SP) to stable single domain (SSD). The software provides the inversion parameters (FDS asymptotes) as well as the limiting frequency effect and transition factor, which provide information regarding contribution of the SP particles to magnetic susceptibility as well as relative variation of the particle grain-size in the SP-SSD transition. Numerical simulations show the procedure's capability in retrieving modeled parameters and fitting data, and its limitation regarding the range of variation of relaxation times. Real data application illustrates the reliability of the procedure for a mineral assemblage in the SP-SSD range.