Figure 3.
Fe@C NPs show enhanced magnetic properties in comparison to Fe3O4 NPs of comparable size. (A) Zero field cooling and field cooling curves for Fe@C NPs (red diamond) compared to 5 nm Fe3O4 NPs (black circles). The applied field was 500 Oe. (B) Magnetic field dependence of magnetization at 10 K. The magnetization of Fe3O4 is scaled 40× in (A) and 5× in (B). The measurements were carried out using a superconducting quantum interference device (SQUID) magnetometer (see Supporting Information).