Effects of iron doping on the transport and magnetic behaviour in La0.65Ca0.35Mn1-yFeyO3

We report on the magnetic and transport measurements in an Fe-doped colossal magnetoresistance compound (La0.65Ca0.35MnO3). Increased spin disorder and a decrease of T-c with increasing Fe content are evident. We find that the resistivity data above T-p fits better to a variable range hopping model and the localization length decreases with Fe content. The variations in the critical temperature T-c, confinement length, magnetic moment and magnetoresistance show a rapid change at about 4-5% Fe. The maximum magnetoresistance is seen to increase consistently with the addition of Fe and increases up to 400% for 8% Fe. The effect of Fe is seen to be consistent with the disruption of the Mn-Mn exchange, possibly due to the formation of magnetic clusters.