COLOSSAL MAGNETORESISTANCE OF DY DOPED (La1-xDyx)0.67Sr0.33MnO3 COMPOUND

Abstract

This work studies the correlation between colossal magnetoresistance (CMR), magnetization and microstructural effect in (La_1-xDy_x)_0.67Sr_0.33MnO₃ when x=0.00, 0.10, 0.20 and 0.40. The magnetoresistance which is defined as MR% = (Ro– R_H)/R_H x 100; was measured by four point probe method over various temperature. All samples exhibit negative colossal magnetoresistance and the magnetoresistance increase proportionally upon substitution of La by Dy, i.e. -12.8%, -21.4% and -26.1% at 1 tesla applied magnetic field while pure LSMO sample MR% is -15.1%. This phenomenon is due to the changed Mn-O-Mn bond angle, caused by the lattice adjusting to the size difference between the La and Dy ions. The XRD patterns reveal that these compounds are orthorhombic distorted perovskite structures and single phase. The AFM images show that the grain sizes reduce when dopant concentrations increase.