THE MAGNETIC-STRUCTURE OF COBALT DIPHOSPHATE CO2P2O7
THE MAGNETIC-STRUCTURE OF COBALT DIPHOSPHATE CO2P2O7
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DOI：
10.1088/0953-8984/1/1/015
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发表时间：
1989-01-09
影响因子：
2.7
通讯作者：
WANKLYN, BM
中科院分区：
文献类型：
--
作者：
FORSYTH, JB;WILKINSON, C;WANKLYN, BM
二磷酸钴在低于 10.20 (5) K 时显示出反铁磁性有序，其磁性结构已通过 3.9 K 下的单晶非极化中子衍射测量确定。该结构包含两个晶体学上独立的 Co (II) 离子，即 Co (1) 和 Co (2)，其矩分别为 3.60 (2) mu B 和 3.62 (2) mu B。磁传播矢量为(1/200)，磁空间群为P 2a 2 1/c。对于 Co (1) 和 Co (2)，该结构与分别以 theta= 82.1 (2) 度、phi=-0.42 (2) 度和 theta= 113.5 (2) 度、phi=-43.7 (2) 度的球极角定向的力矩不共线，极轴平行于从 ac 平面测量的 c 和 phi。 Co 2+ 离子的磁性形状因子显示出相对于自由离子的自由基膨胀，其超出由于其轨道磁化而导致的自由基膨胀。 Co 2+ 离子的(101)片内的磁耦合包括直接路径和超交换路径，而连续片之间的耦合必须通过Co-OPO-Co交换穿过介入的P 2 O 7 基团。讨论了力矩相对于单离子各向异性和磁交换路径的方向。
Cobalt diphosphate is shown to become antiferromagnetically ordered below 10.20 (5) K and its magnetic structure has been determined from single-crystal unpolarised neutron diffraction measurements at 3.9 K. The structure contains two crystallographically independent Co (II) ions, Co (1) and Co (2), with moments of 3.60 (2) mu B and 3.62 (2) mu B, respectively. The magnetic propagation vector is (1/200) and the magnetic space group is P 2a 2 1/c. The structure is noncollinear with the moments oriented at the spherical polar angles of theta= 82.1 (2) degrees, phi=-0.42 (2) degrees and theta= 113.5 (2) degrees, phi=-43.7 (2) degrees for Co (1) and Co (2), respectively, the polar axis being parallel to c and phi being measured from the ac plane. The magnetic form factors of the Co 2+ ions show a radical expansion with respect to the free ion in excess of that due to their orbital magnetisation. Magnetic coupling within the (101) sheets of Co 2+ ions includes both direct and super-exchange paths, whereas the coupling between successive sheets must pass through the intervening P 2 O 7 groups via Co-OPO-Co exchange. The orientations of the moments relative to the single-ion anisotropies and the magnetic exchange paths are discussed.