Magnetic ordering in the rutile molecular magnets M II [N(CN) 2 ] 2 (M=Ni, Co, Fe, Mn, Ni 0.5 Co 0.5 , and Ni 0.5 Fe 0.5 )
Magnetic ordering in the rutile molecular magnets M II [N(CN) 2 ] 2 (M=Ni, Co, Fe, Mn, Ni 0.5 Co 0.5 , and Ni 0.5 Fe 0.5 )
复制标题
金红石分子磁体 M II [N(CN) 2 ] 2 (M=Ni、Co、Fe、Mn、Ni 0.5 Co 0.5 和 Ni 0.5 Fe 0.5 ) 中的磁有序度
DOI：
10.1103/physrevb.67.144406
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发表时间：
2003
影响因子：
3.7
通讯作者：
M. Kurmoo
中科院分区：
文献类型：
--
作者：
A. Lappas;A. Wills;M. Green;K. Prassides;M. Kurmoo
粉末中子衍射数据的 Rietveld 精修，结合群论考虑，用于确定二元金属二氰胺 ${M}^{\mathrm{II}}[{\mathrm{N}(\mathrm{CN})}_{2}{]}_{2}$ 的磁结构，其中 $M=\mathrm{Ni},$ Co, Fe, Mn, ${\mathrm{Ni}}_{0.5}{\mathrm{Co}}_{0.5},$和${\mathrm{Ni}}_{0.5}{\mathrm{Fe}}_{0.5}.$与$M=\mathrm{Mn}$或Fe的化合物显示出在ab晶面取向的倾斜反铁磁自旋排列，两个子晶格的分量沿a 轴并沿 b 轴平行。对称性考虑禁止沿 c 轴出现额外的力矩，无论是否补偿。具有较少不成对电子的化合物（Co 和 Ni）是铁磁体，所有力矩都沿 c 轴定向。 ${\mathrm{Ni}}_{0.5}{\mathrm{Co}}_{0.5}$的混合成分显示出与其母体化合物相同的共线铁磁结构。然而，具有 $M={\mathrm{Ni}}_{0.5}{\mathrm{Fe}}_{0.5},$ 的组合物（其母体化合物表现出不同的磁性行为）并未表现出低至 1.7 K 的长程磁有序性。在我们研究变温粉末中子衍射时，观察到铁磁体的磁致伸缩。富钴化合物表现出更明显的效果，与其不断增加的磁晶各向异性一致。
Rietveld refinement of powder neutron diffraction data, combined with group theory considerations, is used to determine the magnetic structures of the binary metal dicyanamide, ${M}^{\mathrm{II}}[{\mathrm{N}(\mathrm{CN})}_{2}{]}_{2}$ where $M=\mathrm{Ni},$ Co, Fe, Mn, ${\mathrm{Ni}}_{0.5}{\mathrm{Co}}_{0.5},$ and ${\mathrm{Ni}}_{0.5}{\mathrm{Fe}}_{0.5}.$ Compounds with $M=\mathrm{Mn}$ or Fe show a canted antiferromagnetic arrangement of spin oriented in the ab crystallographic plane, with antiparallel components of the two sublattices along the a axis and parallel along the b axis. Symmetry considerations forbid an additional moment, whether compensated or not, to be present along the c axis. The compounds with fewer unpaired electrons (Co and Ni) are ferromagnets, with all moments oriented along the c axis. The mixed composition of ${\mathrm{Ni}}_{0.5}{\mathrm{Co}}_{0.5}$ displays the same collinear ferromagnetic structure as its parent compounds. However, the composition with $M={\mathrm{Ni}}_{0.5}{\mathrm{Fe}}_{0.5},$ whose parent compounds show different magnetic behavior, does not exhibit long-range magnetic ordering down to 1.7 K. Magnetostriction was observed for the ferromagnets for which we investigated the variable temperature powder neutron diffraction. The cobalt-rich compounds show more pronounced effects, consistent with their increasing magnetocrystalline anisotropy.