Co doping effects on the magnetic and magnetoresistance in Sm 0.35Nd 0.35Pb 0.30Mn 1− xCo xO 3 ( x=0, 0.1, 0.2)

Abstract

Polycrystalline samples of the Sm 0.35Nd 0.35Pb 0.35Mn 1− x Co x O 3 ( x=0, 0.1, 0.2) at low magnetic fields has been studied by AC susceptibility, and field cooled and zero field cooled magnetisation measurements. We conclude that a small amount of Co substitution tends to destroy the double exchange and broadens the coexistence region of the cluster-glass and ferromagnetic states. Also, the Co doping suppresses the large negative magnetoresistance and it becomes small for x=0.2.