Experimental studies of strong dipolar interparticle interaction in monodisperse Fe3O4 nanoparticles

Interparticle interaction of monodisperse Fe3O4 nanoparticles has been experimentally investigated by dispersing the nanoparticles in solvents. With increasing the interparticle distances to larger than 100 nm in a controlled manner, the authors found that the blocking temperature (T-B) of the nanoparticles drops continuously and eventually gets saturated with a total drop in T-B of 7-17 K observed for 3, 5, and 7 nm samples, compared with their respective nanopowder samples. By carefully studying the dependence of T-B on the interparticle distance, the authors could demonstrate that the experimental dependence of T-B follows the theoretical curve of the dipole-dipole interaction. (C) 2007 American Institute of Physics.