Cobalt–poly(amido amine) superparamagnetic nanocomposites

Metallic cobalt–dendrimer nanocomposites were prepared using generation 5 poly(amido amine) dendrimers with primary amino termini. Cobalt loading of ∼ 38 atoms per dendrimer was determined by atomic absorption spectrophotometry. Magnetic properties of the cobalt–dendrimer nanocomposites were investigated across the temperature range from 2 to 300 K by SQUID magnetometry. Magnetization as a function of temperature and applied field strength was studied in zero field cooled samples. Magnetization–demagnetization curves (hysteresis loops) were also acquired at temperatures between 10 and 300 K. These results clearly indicate superparamagnetism for the nanocomposites with a characteristic blocking temperature of ∼ 50 K.