  Nanoparticles of the ferrimagnetic epsilon-Fe2O3 oxide have been synthesized
by sol-gel method. Here, we report on the measurements of the dielectric
permittivity as a function of temperature, frequency and magnetic field. It is
found that, coinciding with the transition from collinear ferrimagnetic
ordering to an incommensurate magnetic state occurring at about 100 K, there is
an abrupt change (about 30 %) of permittivity suggesting the existence of a
magnetoelectric coupling in this material. Indeed, magnetic field dependent
measurements at 100 K have revealed an increase of the permittivity by about
0.3 % in 6 T. Prospective advantages of epsilon-Fe2O3 as multiferroic material
are discussed.
