Ferrimagnetism in Ni4Nb2O9.
Ferrimagnetism in Ni4Nb2O9.
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DOI：
10.1103/physrevb.52.9595
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发表时间：
1995-10
期刊：
影响因子：
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通讯作者：
Ehrenberg;Wltschek;Weitzel;Trouw;Buettner;Kroener;Fuess
中科院分区：
文献类型：
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作者：
Ehrenberg;Wltschek;Weitzel;Trouw;Buettner;Kroener;Fuess
对于Pbcn形式的二铌酸镍Ni 4 Nb 2 O 9，在tc = 76.1 (1) k以下观察到铁磁有序，两种磁结构模型计算出的磁反射强度与中子粉末衍射观测到的数据吻合较好。在这两种情况下，磁性结构都由两个相互反平行的镍位组成的铁磁亚晶格组成。一个模型属于磁对称群Pb ' cn ‘，力矩平行[010]，另一个模型属于磁对称群Pbc ’ n '，力矩平行[100]。两个模型的磁矩绝对值分别为：‖μ‖= 1.35 (5)μ B （60 K）和1.65 (5)μ B （1.5 K）。观察到补偿温度T = 33 K，用平均场近似可以用反铁磁性场内和场间耦合之间的竞争来解释磁性。在顺磁区，由居里-魏斯常数得到平均磁矩为3.54 (5)μ B。这些值与Hund规则对Ni 2+的预测很好地吻合。
For the Pbcn form of nickel diniobate Ni 4 Nb 2 O 9 ferrimagnetic ordering is observed below T C= 76.1 (1) K. Two models for the magnetic structure result in calculated intensities for the magnetic reflections, which are in satisfying agreement to the data observed in neutron powder diffraction. In both cases the magnetic structure consists of two ferromagnetic sublattices according to the two Ni sites, which are antiparallel to each other. One model belongs to the magnetic symmetry group Pb′ cn′ with the moments aligned parallel [010] and the other one to Pbc′ n′ with the moments parallel [100]. The absolute values of the magnetic moments, constrained to the same value for both sites, are determined to‖ μ‖= 1.35 (5) μ B (60 K) and 1.65 (5) μ B (1.5 K) for both models. A compensation temperature of T comp= 33 K is observed, and the mangnetic properties can be explained by the competition between antiferromagnetic intrasite and intersite couplings using mean field approximation. In the paramagnetic region an averaged magnetic moment of 3.54 (5) μ B is derived from the Curie-Weiss constant. These values are in good agreement with the predictions by Hund’s rules for Ni 2+.