Direct investigation of superparamagnetism in Co nanoparticle films.
A direct probe of superparamagnetism was used to determine the complete anisotropy energy distribution of Co nanoparticle films. The films were composed of self-assembled lattices of uniform Co nanoparticles of 3 or 5 nm in diameter, and a variable temperature scanning-SQUID microscope was used to measure temperature-induced spontaneous magnetic noise in the samples. Accurate measurements of anisotropy energy distributions of small volume samples will be critical to magnetic optimization of nanoparticle devices and media.
Woods
S I
SI
IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA.
Kirtley
J R
JR
Sun
S
S
Koch
R H
RH