  We investigated magnetic properties of the L10-FePt nanoparticles synthesized
by the SiO2-nanoreactor method by means of Moessbauer spectroscopy from the
microscopic point of view. Almost all of the nanoparticles were revealed to
have nearly the same Moessbauer hyperfine parameters as those of the bulk
L10-FePt alloy, indicating that they have well-defined L10 structure equivalent
to the bulk state in spite of their small size of 6.5 nm.
