Magnetoelectric Interactions in Multiferroic Nanocomposites
In materials that are magnetoelectric, the induced polarization P is related to the šeld H by the expression, P = αH, where α is the second rank ME-susceptibility tensor and is expressed in the units of s/m in SI units (in Gaussian units α = 4πP/H = 4πM/E is dimensionless). One generally determines α by measuring Pz for an applied šeld H along the z-axis. Another parameter of importance is the ME voltage coeÀcient αE = E/H which
is related to α by the expression α = εoεrαE, where εr is the relative permittivity of the material. Several single-phase materials that are either antiferromagnetic, weak ferromagnetic, or ferrimagnetic, such as Cr2O3, TbFeO3, and FexGa2−xO3, show rather weak ME e£ects [7-12].