Extraction of “hidden” relaxation times from AC susceptibility data

Abstract

Magnetic relaxation times are the central observable in defining the characteristics of single-molecule magnets. It is not uncommon to observe multiple distinct relaxation timescales for a pure material, and sometimes only one relaxation timescale is observed in samples containing multiple components. Herein we examine the conditions required for two distinct relaxation processes to be observable in alternating current susceptibility experiments. We find that there must be at least one order of magnitude difference in the two relaxation times I log10[taumu,1/taumu,2] I > 0.922, even when the intrinsic distributions of the two processes are infinitely sharp (alpha = 0 in the generalised Debye model). In the case where only one process is observable, we provide an expression to estimate the two underlying relaxation times, allowing extraction of “hidden” information from AC susceptibility data.