Sm0.45Sr0.55MnO3: crystal and magnetic structure studied by neutron powder diffraction

The crystal and magnetic structures of the manganite 152Sm0.45Sr0.55MnO3 have been established by high resolution neutron powder diffraction. These data are compared with the magnetic and transport properties of this compound. Firstly, it is found that this manganite crystallizes in a perovskite-like structure belonging to the orthorhombic system (Pnma) in the entire temperature range under study (1.5-260 K). Secondly, this study reveals that the magnetic and electronic ground states of 152Sm0.45Sr0.55MnO3 at low temperatures correspond to a homogeneous A-type antiferromagnetic insulator (TN∼180 K) with dx2-y2 type orbital ordering. The lack of magnetoresistance for this composition is explained by the lack of coexisting magnetic phases involving ferromagnetism, in contrast to what is observed for the magnetoresistive Sm1-xSrxMnO3 compounds, that is with x≤0.52