Magnetic transport behavior of nano-crystalline Pr0.67A0.33MnO3 (A = Ca, Sr, Pb and Ba) manganites

With a view to understand the magneto transport behavior of Pr0.67A0.33MnO3 (A = Ca, Sr, Pb and Ba) exhibiting colossal magnetoresistance behavior, a systematic investigation has been undertaken. For this purpose, samples were prepared by poly vinyl alcohol (PVA)-gel route and after structural characterization of the samples by X-ray diffraction (XRD) and SEM, the electrical and magnetic transition temperatures (TC and TP) were determined. The variation of both the transition temperatures is explained on the basis of size variance parameter. A systematic investigation of magnetization as a function of both magnetic field and temperature has been undertaken. It has been found from the magnetization versus temperature plot of PCMO that it exhibits reentrant type of spin glass behavior at 44 K. It has been concluded from the M-H plots that these materials are having soft ferromagnetic nature. Finally, of all the four samples under investigation, Pr0.67Pb0.33MnO3 is found to exhibit highest magnetoresistance (MR) of 97%.