Magnetic properties of single domain samarium cobalt nanoparticles

Samarium cobalt nanoparticles were prepared by ball milling under argon, both with and without surfactant. X-ray diffraction indicated a single SmCo/sub 5/ phase, with an average size of 25 nm from Debye-Scherrer analysis of the peak widths, but a broad size distribution based on TEM. SQUID magnetometry yielded the coercivity as a function of temperature between 4 and 300 K. Large coercivities (H/sub c/=2.1 T at 10 K) were observed in the bare particles, but the values were significantly reduced (H/sub c/=0.12 T at 5 K) for those coated with surfactant, indicating probable surface oxidation.