LAUSR

Abstract The magnetoresistance (MR) and magnetism of PrBaCo2O5+δ (PBCO) with different oxygen content are systematically investigated. It is found that with the temperature lowing, the MR effect changes from positive to negative for the sample annealed in Ar with low oxygen content, and is negative and increases in magnitude for the as-prepared and O2-annealed samples (AP-PBCO, O2–PBCO). A higher MR effect with ∼38% at around 70 K and 9 T for AP-PBCO is obtained. Besides, an abnormal decrease in magnitude for MR is observed for AP-PBCO and O2–PBCO. It is suggested that the spin disorder related polaron hopping energy WP is crucial for the MR effect in PBCO, besides the competition of AFM and FM interactions, which rests with the crystal structure dominated by the content and order of the oxygen vacancies. The observed abnormal MR can be attributed to the reduced polaron hopping energy WP related to the AFM order. The results not only experimentally confirm that the MR effect can be easily adjusted by the oxygen vacancies but also open up a new way for developing the high MR in layered double perovskites for application.