Independent Ordering of Two Interpenetrating Magnetic Sublattices in the Double Perovskite Sr2CoOsO6
Independent Ordering of Two Interpenetrating Magnetic Sublattices in the Double Perovskite Sr2CoOsO6
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DOI：
10.1021/ja407342w
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发表时间：
2013-12-18
影响因子：
15
通讯作者：
Woodward, Patrick M.
中科院分区：
文献类型：
--
作者：
Morrow, Ryan;Mishra, Rohan;Woodward, Patrick M.
绝缘的，完全有序的，双钙钛矿Sr 2CoOsO 6经历两个磁相变。Os（VI）离子在低于T-N1 = 108 K时具有反铁磁有序，传播矢量k =（1/2，1/2，0），而高自旋CO（II）离子在低于T-N2 = 70 K时具有反铁磁有序，传播矢量k =（1/2，0，1/2）. Os（VI）自旋的有序化伴随着从四斜晶系14/m对称到单斜晶系I2/m对称的结构畸变，这减少了Os（VI）离子的面心立方晶格的挫折。密度泛函理论计算结果表明，长程Os-O-Co-O-Os和Co-O-Os-O-Co超交换作用比短程Os-O-Co强得多. Co的3d轨道和Os的5d轨道之间的能量差重叠似乎是造成这种不寻常的反转的短距离和长距离超交换相互作用的强度的原因。
The insulating, fully ordered, double perovskite Sr2CoOsO6 undergoes two magnetic phase transitions. The Os(VI) ions order antiferromagnetically with a propagation vector k = (1/2, 1/2, 0) below T-N1 = 108 K, while the high-spin CO(II) ions order antiferromagnetically with a propagation vector k = (1/2, 0, 1/2) below T-N2 = 70K. Ordering of the Os(VI) spins is accompanied by a structural distortion from tetragonal 14/m symmetry to monoclinic I2/m symmetry, which reduces the frustration of the face centered cubic lattice of Os(VI) ions. Density functional theory calculations show that the long-range Os-O-Co-O-Os and Co-O-Os-O-Co superexchange interactions are considerably stronger than the shorter Os-O-Co interactions. The poor energetic overlap between the 3d orbitals of Co and the 5d orbitals of Os appears to be responsible for this unusual inversion in the strength of short and long-range superexchange interactions.