Neutron diffraction study of crystal and magnetic structure of samarium-strontium manganite

Neutron-powder-diffraction experiments on (Sm0.6Sr0.4MnO3)-Sm-154 in temperature range (1.5-300 K) have been performed using G4.2 (LLB, France) diffractometer. The sample we investigate undergoes insulator-metal transition at T similar to 110 K and demonstrates maximum of colossal magnetoresistance effect at the same temperature. The crystal structure is orthorhombic (Pbnm) for all measured temperatures, but metrically close to tetragonal at room temperature. The room temperature is found to be close to the Jahn-Teller transition temperature. The temperature dependence of microstrain parameter related to anisotropic peak's broadening is obtained. Magnetic scattering detected for T<130 K can be formally attributed to the canted ferromagnetic state. The saturated magnetic moment of Mn-ions at T=1.5 K was found to be equal similar to 2.5 mu(B). The consequences of our experimental results are discussed in the context of current ideas about structure and magnetotransport properties of manganites.