Figure 5.

Longitudinal nonlinear response measured at the second harmonic of the M₂ magnetization for a bioconjugate of magnetic nanoparticles (MNP-C). Phase component ReM₂ of the second harmonic of magnetization as a function of constant field H for aqueous dispersions of MNP-C at H-scan frequencies (a) 0.25 Hz and (b) 8 Hz. The response signals were recorded at a temperature of 294 K. The concentration of iron (in terms of Fe³⁺) in the sample was 0.02 mM/L, the sample volume was 500 μL. Solid symbols denote data obtained during the direct sweep of the H field, open symbols denote data obtained during the reverse course of the H-scan.