我们报告了三重钙钛矿铱酸盐Ba $_{3}$ CoIr $_{2}$ O $_{9}$的全面调查。在室温下稳定于六方$P6_{3}/mmc$对称性，该系统在磁相变时转变为单斜$C2/c$对称性。在温度进一步降低时，系统部分地扭曲到甚至更低的对称性（$P2/c$），这两种结构上不同的相共存到最低的测量温度。从中子衍射数据确定的磁性结构表明，弱倾斜的反铁磁结构，这也是支持第一性原理计算。理论表明Ir $^{5+}$具有有限的磁矩，这也与中子数据一致。这表明避免了假定的PDMATHAMT状态。测量的热容，电阻噪声和介电敏感性都指向一个高度相关的Ba $_{3}$ CoIr $_{2}$ O $_{9}$系统的基态的稳定。
英文摘要：
We report a comprehensive investigation of the triple perovskite iridate Ba$_{3}$CoIr$_{2}$O$_{9}$. Stabilizing in the hexagonal $P6_{3}/mmc$ symmetry at room temperature, this system transforms to a monoclinic $C2/c$ symmetry at the magnetic phase transition. On further reduction in temperature, the system partially distorts to an even lower symmetry ($P2/c$), with both these structurally disparate phases coexisting down to the lowest measured temperatures. The magnetic structure as determined from neutron diffraction data indicates a weakly canted antiferromagnetic structure, which is also supported by first-principles calculations. Theory indicates that the Ir$^{5+}$ carries a finite magnetic moment, which is also consistent with the neutron data. This suggests that the putative $J=0$ state is avoided. Measurements of heat capacity, electrical resistance noise and dielectric susceptibility all point towards the stabilization of a highly correlated ground state in the Ba$_{3}$CoIr$_{2}$O$_{9}$ system.
Tuning Magnetic and Electronic Properties of Double Perovskite La$_2$CoIr$_{1-x}$Ti$_x$O$_6$
Indian Institute of Technology Tirupati（印度理工学院提鲁帕蒂分校）；Indian Institute of Technology Mandi（印度理工学院曼迪分校）；Indian Association for the Cultivation of Science（印度科学培育协会）
本研究通过 Ti 掺杂和静水压调控双钙钛矿 La$_2$CoIr$_{1-x}$Ti$_x$O$_6$，结合磁化、热膨胀与 DFT 计算，揭示其磁态转变、压磁效应及带隙展宽机制。
Magnetic excitations in double perovskite iridates La$_{2}$$\mathit{M}$IrO$_{6}$ ($\mathit{M}$ = Co, Ni, and Zn) mediated by 3$\mathit{d}$-5$\mathit{d}$ hybridization
