  Morphology, structure and magnetic properties of nanocomposites of magnetite
(Fe3O4) nanoparticles and alginic acid (AA) are studied. Magnetite Fe3O4
nanoparticles and the nanoparticles capped with alginic acid exhibit very
distinct properties. The chemical bonding between alginic acid and surface of
magnetite nanoparticles results in recovery of surface magnetization. On the
other hand, it also leads to enhanced surface spin disorder and unconventional
behavior of magnetization observed in Fe3O4-AA nanocomposites at low
temperatures.
