Crystal structure and magnetic ordering of Mn and Ce in La0.7Ce0.15Ca0.15MnO3

Neutron diffraction, ac magnetic susceptibility and magnetization measurements have been performed to study the magnetic properties of Ce-doped La0.7Ce0.15Ca0.15MnO3. A slightly distorted monoclinic P 21 /c symmetry for the crystal structure was found to describe the high-resolution powder diffraction pattern, taken at room temperature, better than the normally used orthorhombic Pnma symmetry does. Three anomalies, at around 165, 105 and 38 K, were clearly evident in the ac susceptibility measurements. Neutron diffraction measurements then confirmed that the anomaly at high temperature is associated with the ferromagnetic ordering of the Mn spins, whereas the low-temperature one corresponds to the ordering of the Ce spins. The ordering temperatures for the Mn and Ce spins were found to be at TC (Mn) 180 K and TC (Ce) 45 K, respectively, with a saturated moment of (μz ) = 2.54(5)μB for the Mn spins and an average moment of 0.27(3)μB on the rare-earth sites