Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan.
J Phys Condens Matter. 2010 May 5;22(17):176003. doi: 10.1088/0953-8984/22/17/176003. Epub 2010 Apr 12.
Magnetic and structural phase diagram in a spinel-type solid solution system Fe(1-x)Mn(x)Cr(2)O(4) has been investigated. The cubic-to-tetragonal transition temperature T(s 1) is gradually reduced by the substitution of Mn(2+) (3d(5)) for Jahn-Teller-active Fe(2+) (3d(6)) ions, implying the long-range nature of the ferroic interaction between orbitals. In the paramagnetic tetragonal phase for x < 0.5, the c parameter is shorter than a because of the anharmonicity of the elastic energy. The crystal structure further changes to orthorhombic at around the ferrimagnetic transition temperature T(N 1). T(s 1) and T(N 1) meet at x = 0.5, and Mn substitution of more than 0.5 gives rise to another tetragonal phase with a < c. The systematic change in crystal structure is discussed in terms of competition between the anharmonic lattice potential and the intra-atomic spin-orbit interaction at Fe(2+).
尖晶石型固溶体系统 Fe(1-x)Mn(x)Cr(2)O(4) 的磁性和结构相图已经被研究过了。由于 Jahn-Teller 活性的 Fe(2+) (3d(6)) 离子被 Mn(2+) (3d(5)) 取代，立方到四方的转变温度 T(s 1)逐渐降低，这表明轨道之间的铁电相互作用具有长程性质。在 x < 0.5 的顺磁四方相中，由于弹性能量的非谐性，c 参数比 a 参数短。在铁磁共振转变温度 T(N 1)左右，晶体结构进一步变为正交晶系。T(s 1)和 T(N 1)在 x = 0.5 处相遇，超过 0.5 的 Mn 取代导致另一个具有 a < c 的四方相。晶体结构的系统变化是根据 Fe(2+) 中的非谐晶格势和原子内自旋轨道相互作用之间的竞争来讨论的。
