Spin-lattice instability to a fractional magnetization state in the spinel HgCr2O4
Spin-lattice instability to a fractional magnetization state in the spinel HgCr2O4
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DOI：
10.1038/nphys586
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发表时间：
2007-06-01
期刊：
影响因子：
19.6
通讯作者：
Lee, S.-H.
中科院分区：
文献类型：
--
作者：
Matsuda, M.;Ueda, H.;Lee, S.-H.
磁系统是奇异态出现的肥沃土壤（1），当磁相互作用由于晶格的拓扑结构而不能同时满足时-这种情况称为几何挫折（2，3）。尖晶石AB（2）O（4）可以实现角共享四面体（1-3）的最高阻挫网络。在尖晶石中发现了几种新的态，如复合自旋团簇（1）和新的电荷有序态（4-6）。在这里，我们使用中子和同步加速器X射线散射来表征HgCr 2 O 4在外磁场H下的分数磁化状态。当施加在其Neel基态的场时，在类似于10 T的H处发生相变，其中每个四面体从倾斜的Neel状态改变为具有S/2的总自旋S-tet的分数自旋状态，并且晶格经历正交到立方对称性的变化。我们的结果提供了自旋态和晶格畸变之间的微观一一对应。
Magnetic systems are fertile ground for the emergence of exotic states(1) when the magnetic interactions cannot be satisfied simultaneously owing to the topology of the lattice - a situation known as geometrical frustration(2,3). Spinels, AB(2)O(4), can realize the most highly frustrated network of corner-sharing tetrahedra(1-3). Several novel states have been discovered in spinels, such as composite spin clusters(1) and novel charge-ordered states(4-6). Here, we use neutron and synchrotron X-ray scattering to characterize the fractional magnetization state of HgCr2O4 under an external magnetic field, H. When the field is applied in its Neel ground state, a phase transition occurs at H similar to 10 T at which each tetrahedron changes from a canted Neel state to a fractional spin state with the total spin, S-tet, of S/2 and the lattice undergoes an orthorhombic to cubic symmetry change. Our results provide the microscopic one-to-one correspondence between the spin state and the lattice distortion.