Structure and magnetism of BaTi1-xFexO3-δ multiferroics.

The effect of Fe dopant content, x, on the magnetism of polycrystalline BaTi1-xFexO3-δ (BTFO) multiferroic samples was investigated using magnetization measurements in correlation with the crystallographic and local structures. The changes of coercivity and magnetization as functions of x are closely related to the variation of oxygen vacancy content, δ, which can be deduced from the Fe oxidation number estimation using Fe K-edge x-ray absorption spectroscopy. It is shown that although the samples exhibit ferromagnetic (FM) hysteresis at room temperature, a dominant paramagnetic phase coexisting with the FM phase makes it difficult to identify the FM contribution to the total magnetization. Spin-glass and/or superparamagnetic behavior may be ruled out due to the fact that both zero-field-cooled and field-cooled thermomagnetization curves almost totally overlap together over the whole range of measured temperatures. [ABSTRACT FROM AUTHOR]