Structural study on the phase separation in Sm_(1-x)Ca_xMnO_3 (0.8 ≤ x ≤ 0.92)

摘要

We have investigated the details of phase separation in the electron-doped manganites Sm_(1-x)Ca_xMnO_3 (0.8 ≤ x ≤ 0.92) by using temperature dependent x-ray diffraction. The lattice of the low-temperature orthorhombic phase is distorted to various extents according to the strength of the coexisting monoclinic phase. Meanwhile, the room-temperature lattice becomes more distorted due to the increasing Jahn-Teller active Mn~(3+) ions by Sm~(3+) doping. On the other hand, the substitution of Ca~(2+) with Sm~(3+) introduces the Mn~(3+)-Mn~(4+) pairs, which favor the double exchange ferromagnetism. As a result of the competition between the lattice distortion and electron doping level, the modified phase diagram have been presented, including the high-temperature Griffiths phase and the ground state with competing multiphases.