Dielectric behaviour of a ferrofluid subjected to a uniform magnetic field

The electric susceptibility of samples of ferrofluids subjected to a uniform magnetic field H was measured. The electric susceptibility \chi is dependent on the magnitude of the magnetic field and on the relative direction between the electric field E and the magnetic field H . 1) When E is perpendicular to H, \frac{\partial\chi_{\perp}}{\partialH} 2) When E is parallel to H, \frac{\partial\chi_{\parellel}}{\partialH} > 0 These results have been interpreted as a magneto-electric directive effect. A model is proposed, based on the assumption that the magnetic particles are roughly ellipsoidal and conducting grains.