Identifying the contribution of band filling effects in the double perovskite system

This work investigates various factors affecting the Curie temperature in double perovskite A2FeMoO6 systems and the contribution of band filling effects for various parameters. The measurements were conducted on Sr0.4Ba1.6FeMoO6 samples prepared at different sintering temperature and a series of trivalent and divalent substituted Sr0.4Ba1.6−xAxFeMoO6 samples (A=La3+, Sr2+). A careful investigation allowed delineating the contributions of pristine band filling. The contribution of band filling effects to the Curie temperature increase is observed to be 1.5 K for each percent of trivalent substitution (about 60% of total increase in the present study). For an equal decrease of the A site cation radii, the changes observed in the lattice parameter for trivalent and divalent doped stems exhibited differences up to 33%. The increase in unit cell length (the a value) associated with band filling is thus 9.35×10−4 Å for each percent of trivalent doping. It is also observed that a moderate level of impure phases and disorder defects plays a minor role in determining the Curie temperature of such a system.