Faculty of Physics , Moscow State University , Moscow 119991 , Russia.
National Research South Ural State University , Chelyabinsk 454080 , Russia.
Inorg Chem. 2020 Jan 21;59(2):1532-1546. doi: 10.1021/acs.inorgchem.9b03423. Epub 2020 Jan 8.
MnSnTeO, a new chiral antiferromagnet, was prepared both by topotactic transformation of the metastable rosiaite-type polymorph and by direct synthesis from coprecipitated hydroxides. Its structure and its static and dynamic magnetic properties were studied comprehensively both experimentally (through X-ray and neutron powder diffraction, magnetization, specific heat, dielectric permittivity, and ESR techniques) and theoretically (by means of density functional theory (DFT) calculations within the spin-polarized generalized gradient approximation). MnSnTeO is isostructural with MnSbO (space group 321) and does not show any structural transition between 3 and 300 K. The magnetic susceptibility and specific heat exhibit an antiferromagnetic ordering at ≈ 9.8 K, which is confirmed by low-temperature neutron data. At the same time, the thermodynamic parameters demonstrate an additional anomaly on the temperature dependences of magnetic susceptibility χ(), specific heat () and dielectric permittivity ε() at * ≈ 4.9 K, which is characterized by significant temperature hysteresis. Clear enhancement of the dielectric permittivity at * is most likely to reflect the coupling of dielectric and magnetic subsystems leading to development of electric polarization. It was established that the ground state of MnSnTeO is stabilized by seven exchange parameters, and neutron diffraction revealed incommensurate magnetic structure with propagation vector = (0, 0, 0.183) analogous to that of MnSbO. DFT calculations demonstrate that the strongest exchange coupling occurs between planes along diagonals. All exchange parameters are antiferromagnetic and reveal moderate frustration.
MnSnTeO 是一种新的手性反铁磁体，可通过亚稳罗西亚型多晶型物的拓扑转变和直接从共沉淀的氢氧化物合成制备。通过实验（通过 X 射线和中子粉末衍射、磁化、比热、介电常数和 ESR 技术）和理论（通过密度泛函理论（DFT）计算在自旋极化广义梯度近似内）对其结构及其静态和动态磁性能进行了全面研究。MnSnTeO 与 MnSbO（空间群 321）具有相同的结构，并且在 3 至 300 K 之间没有任何结构转变。磁化率和比热在 ≈ 9.8 K 处表现出反铁磁有序，这通过低温中子数据得到了证实。同时，热力学参数在磁磁化率 χ()、比热 () 和介电常数 ε()的温度依赖性上显示出额外的异常在 * ≈ 4.9 K 处，其特征是温度滞后显著。在 * 处介电常数的明显增强很可能反映了介电和磁子系统的耦合，导致电极化的发展。已经确定 MnSnTeO 的基态是由七个交换参数稳定的，并且中子衍射揭示了具有传播矢量 = (0, 0, 0.183)的非共调磁结构，类似于 MnSbO 的磁结构。DFT 计算表明，最强的交换耦合发生在对角线方向的平面之间。所有交换参数均为反铁磁且具有中等程度的挫折。
