Magnetotransport Behaviour of Nanocrystalline Pr1-xSrxMnO3

The nanocrystalline samples ofPr 1 - xSr xMnO 3(PSMO) ( x = 0.40 , 0.50, 0.55, and 0.60) were synthesized by wet-chemical sol-gel route. Structural, magnetic, and magnetotransport properties have been studied systematically. It is found thatPr 1 - xSr xMnO 3samples with Sr content x = 0.40 and 0.50 show paramagnetic to ferromagnetic (PM-FM) transition atT C ~ 308  K with no trace of FM-AFM transition within the temperature range of 77–350 K. However, interestingly a second transition is observed at T~ 273 and 255 K, respectively, for samples x = 0.55 and 0.60 correspond to an A-AFM magnetic structure. This indicates that samples x = 0.40 and 0.50 are ferromagnetic belowT C, while other samples ( x = 0.55 and 0.60) have a mixed phase consisting of FM and A-type AFM phases. Resistivity versus temperature ( ρ - T ) curve shows that the resistivity of all the samples is much larger than the single crystals of corresponding compositions due to large contribution of grain boundaries in the present nanocrystalline samples. Moreover, the decrease in metallic component at higher Sr concentration is also evidenced by the successive reduction in magnetoresistance (MR) with increasing Sr content from x = 0.40 to 0.60.