Magnetization modulation by ferroelectric polarization switching is reported for the ferromagneticferroelectric EuO/BaTiO3 heterostructure. The value of the magnetization critical exponent b is consistent with the expected Heisenberg-like ferromagnetism of EuO and reported Curie temperature. The critical exponent is seen to decrease with increased magnetic coupling. The results are discussed in the context of data obtained earlier for epitaxial La0.67Sr0.33MnO3/BaTiO3 heterostructures, where magnetization increases and critical exponent b also declines with ferroelectric polarization pointing away from ferromagnetic layer. The observed similarity between two systems illustrates an importance of charge doping in magnetoelectric coupling, which can be modulated by ferroelectric polarization reversal. Copyright 2013 AIP Publishing LLC.