Magnetic and electrical properties of high-entropy rare-earth manganites

Abstract

Detailed investigations of structural, magnetic and electronic transport properties of hole-doped high-entropy rare-earth manganites are presented. The high-entropy samples (La0.2Nd0.2Pr0.2Sm0.2Eu0.2)1−xSrxMnO3 (0 ≤ x ≤ 0.5), synthesized using the solid-state technique, show a change in the crystal structure from Pbnm to R-3c with increasing Sr substitution, attributed to the change in the tolerance factor. Prominent ferromagnetic ordering is observed in the sample with a rhombohedral structure (x ≥ 0.3), originating from the dominant double exchange mechanism mediated by itinerant electrons. Further, the Curie temperature is smaller for the high-entropy sample with x=0.3, as compared to La0.7Sr0.3MnO3, suggesting a strong relation between the Curie temperature and the Mn–O–Mn bond angle associated with the reduced ionic radii at the rare-earth site. The electrical resistivity of the high-entropy samples is larger than those of La1−xSrxMnO3, which can be ascribed to the reduced bandwidth due to the enhanced structural distortion. A concomitant rise in magnetoresistance is observed for high-entropy samples with the increase in Sr concentration. These findings considering the configurational complexity of different rare-earths advance the understanding of high-entropy rare-earth manganites.