Figure 5. Magnetic characterisation of the multi-core particles at T = 300 K.

(a) Initial magnetisation curve of M_im(H) from Fig. 4, fit with equation 6 under assumption of a log-normal distribution p_V(μ) and reconstructed data set (numerical inversion). Inset: Residuals of the log-normal fit and of the numerical inversion. (b) Log-normal distribution of magnetic moments determined by fitting M_im(H) with equation 6. The fitting curve with artificially added noise was numerically inversed, resulting in the distribution (dashed line shows the extracted distribution in case of a reduced regularisation parameter). With the same numerical approach the distribution was extracted from the experimental data M_im(H). (c) Initial magnetisation curves of M_di(H) and M_im(H) from Fig. 4 and the reconstructed data sets and . For the reconstruction the moment distributions and from Fig. 5(d) were used. (d) Discrete moment distributions (from Fig. 5(b)) and determined by numerical inversion of the initial magnetisation curves of M_im(H) and M_di(H). The distribution P_size(μ) was calculated for a particle ensemble with a mean core size from a log-normal distribution of 6.6 nm (σ = 0.28).