Fig. 6: Hysteresis of the magnetic chain-like structures.
a The magnetic behavior comprises stabilizing exchange interactions among the individual particles and the stabilizing effects of the nanochains themselves. The alignment of the nanochains results in an additional drop in magnetization with increasing magnetic field strength (see dashed inlet), exemplified for an aqueous or an 80 wt.% glycerol/water dispersion of sample CF-S2-1 (bright blue), synthesized with the precursor aka@0.40PAA@2.5SiO2. b The squareness ratios and coercivity values in water exhibit the same parabola trend, with these values increasing with the cobalt-to-iron ratio until a maximum is reached at approximately 0.18, synthesized at a temperature of 160 °C and a filling volume of 100%. With increasing c diameter and d Co/Fe ratio of the samples dispersed in 80 wt.% glycerol/water, the squareness ratios and coercivities of the CF-S samples (synthesized with different silica thicknesses, filled) are adjustable compared to those of CF-A (synthesized with aka, hollow) and CF-P samples (synthesized with aka@PAA, half-filled). e Using the hysteresis loops, the differential magnetization of the exemplary CF-S2-1 curves can be calculated, which shows a maximum at H = 0 (static mass susceptibility). The saturation magnetization and the static mass susceptibility of all samples in 80 wt.% glycerol/water are depicted in dependence on the f diameter and g Co/Fe ratio, recording a rising trend for each.
