Spin glass-like behavior, giant magnetocaloric and giant magnetoresistance effect in PrPb manganites

The Pr1−xPbxMnO3 (x=0.1-0.5) perovskites have been fabricated by solid-state reaction. The X-ray diffraction patterns show that the samples are of single phase with orthorhombic structure. The field-cooled (FC) and zero-field-cooled (ZFC) thermomagnetic curves measured at low field and low temperatures exhibit the spin glass-like state. The Curie temperature of samples increased with increase in Pb content. The maximum magnetic entropy change |ΔSm|max reaches the giant values of 3.91 and 3.68 J/kg K for quite low magnetic field change of 1.35 T for the samples x=0.1 and 0.4, respectively. The resistance measurements show that there is insulator-metal phase transition on the R(T) curves for samples with x⩾0.3. The giant magnetoresistance effect is also observed for all samples studied.