Physics of magnetic fluids

This paper reviews various fundamental physical properties of magnetic fluids, such as superparamagnetic behavior, neutron-depolarization, magneto-viscosity, anisotropic attenuation of sound waves and magneto-optical properties and discusses how these properties are explained in terms of the nature of colloidal particles, particularly in relation to their cluster formation. Emphasis is placed on the explanation of recent experiments on the magneto-optical dichroism and birefrengence in terms of Rayleigh scattering of the ray from the elongated clusteres of the magnetic particles.