Effects of the band-filling and Fe/Mo disorder on physical properties of Ca2FeMoO6

Both the band filling effect and Fe/Mo disorder have a close correlation with the physical properties of the double perovskite Ca2FeMoO6. Two series of Ca2FeMoO6 and Nd0.3Ca1.7FeMoO6 ceramics sintered at (1050 degrees C, 1200 degrees C, and 1300 degrees C) were specially designed to comparatively investigate the band-filling effect and Fe/Mo disorder on the physical properties of Ca2FeMoO6. The x-ray diffraction indicates that Fe/Mo disorder is sensitive to the sintering temperature. The magnetization behavior is mainly controlled by the Fe/Mo disorder not by the band filling effect, manifested by a close correlation of saturated magnetization (M-s) with the Fe/Mo disorder. Interestingly, magnetoresistance (MR) property of the same composition is dominantly contributed by the grain boundary strength, which can be expressed by the macroscopic resistivity values. However, the band filling effect caused by the Nd-substitution can decrease the spin polarization, and thus suppress the MR performance fundamentally. Contrary to the MR response, the Curie temperature (T-C) shows an obvious optimization due to the band filling effect, which increases the carrier density near the Fermi level responsible for the ferromagnetic coupling interaction strengthen. Maybe, our work can provoke further research interests into the correlation of the band-filling effects and Fe/Mo disorder with the physical properties of other Fe/Mo-based double perovskites.