Syntheses and Characteristics of R-P Phase $Ln_{1-x}Sr_{2-x}Mn_2O_7$(Ln=La, Pr, Gd, Eu, Er, Nd, Sm)

R-P Phase $Ln_{1-x}Sr_{2-x}Mn_2O_7$(Ln=La, Pr, Gd, Eu, Er, Nd, Sm)의 합성 및 특성연구

Since the first reports of CMR(colossal magnetoresistance) effects in some single crystal R-P Phase Ln$_{1-x}$ Sr$_{2-x}$Mn$_{2}$O$_{7}$ 1996. many researches have been carried out to find optimum compositions and processing conditions in this system. In this study, layered perovskite R-P Phase Ln$_{1-x}$ Sr$_{2-x}$Mn$_{2}$O$_{7}$ (x=0.4, Ln=-La, Eu, Gd, Nd, Pr, Sm) phases were synthesized by solid state reaction and their structures were refined by Rietveld method. Electrical and magnetic properties were measured drown to 20K and compare with those of R-P Phase Ln$_{1-x}$ Sr$_{2-x}$Mn$_{2}$O$_{7}$ Phases.es.es.es.es.es.