Magnetic Ordering and Relation to the Metal-Insulator Transition inPr1−xSrxMnO3andNd1−xSrxMnO3withx∼1/2

Abstract

We studied three distorted perovskite manganites, Pr{sub 1/2}Sr {sub 1/2}MnO {sub 3} and Nd{sub 1-x}Sr {sub x}MnO{sub 3} with x=1/2 and 0.55 by the neutron diffraction technique. Two samples with x=1/2 exhibit a transition from a ferromagnetic (FM) metal to an antiferromagnetic (AFM) nonmetal. We demonstrate that, in the low temperature phase, Nd{sub 1/2}Sr {sub 1/2}MnO {sub 3} has a CE-type AFM structure with charge ordering, while Pr{sub 1/2}Sr {sub 1/2}MnO {sub 3} and Nd{sub 0.45} Sr{sub 0.55} MnO{sub 3} exhibit an A-type layered AFM structure, but show no clear sign of charge ordering. From the present results, we suggest a possible anisotropy of transport as well as magnetic properties in the A-type AFM structure near x{approximately}1/2. {copyright} {ital 1997} {ital The American Physical Society}