固定1/3填充的反钙钛矿（Li₂M）ChO（M=Fe、Mn、Co；Ch=S、Se）稀释磁体中的磁性：磁各向异性的关键作用
Magnetism in antiperovskite (Li$_2$\textit{M})\textit{Ch}O (\textit{M} = Fe, Mn, Co; \textit{Ch} = S, Se) diluted magnets with fixed 1/3 filling: the key role of magnetic anisotropy
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中文总结 AI 辅助
本研究探究固定1/3填充的反钙钛矿稀释磁体的磁性，发现磁各向异性是决定奈尔温度的关键参数，磁稀释会降低有序温度，且不同过渡金属的奈尔温度存在明显差异。
中文摘要 AI 辅助
我们报道了一系列富锂反钙钛矿（Li₂M）ChO（M=Fe、Co、Mn，Ch=Se、S）的磁性，其中过渡金属离子与锂离子随机分布在X₃BA结构的X位，形成强稀释的磁性亚晶格。因此，本研究可在固定1/3填充（该填充率接近但略高于渗流阈值）的情况下，探究自旋尺寸、磁各向异性和轨道构型变化时磁有序的演化。数据表明，直至350K未观察到明显的居里-外斯行为，反而呈现出较大且弱温度依赖的磁化率。我们观测到，在1/3填充的强稀释磁性X位晶格中，随着奈尔温度（T_N）升高，长程反铁磁有序的清晰特征逐渐显现：（Li₂Mn）ChO的T_N约为30K，（Li₂Fe）ChO的T_N约为50K，（Li₂Co）ChO的T_N为70-90K。除M=Co外，硫族元素对T_N无显著影响。我们得出结论，在远高于T_N时存在显著的磁耦合与短程磁关联，这与室温下观测到的宽电子自旋共振信号一致。磁稀释会大幅降低实际有序温度；尽管容忍因子和键角等结构参数对T_N影响不大，但过渡金属的磁各向异性是关键参数。
英文摘要
We report the magnetic properties of a series of lithium-rich antiperovskites (Li$_2M$)$Ch$O ($M$ = Fe, Co, Mn and $Ch$ = Se, S) where transition metal and lithium ions are randomly distributed on the X-sites of the X$_3$BA structure, thereby forming a strongly diluted magnetic sublattice. Our study hence enables us to investigate the evolution of magnetic order at fixed 1/3-filling -- which is in the vicinity but slightly above the percolation threshold -- upon variation of the spin size, the magnetic anisotropy, and the orbital configuration. The data imply the absence of a distinct Curie-Weiss behavior up to 350~K but show rather large and weakly temperature-dependent magnetic susceptibility. We observe clear signatures of long-range antiferromagnetic order evolving in the 1/3-filled and strongly diluted magnetic X-site lattice with increasing Néel temperatures from $T_{\rm{N}}\simeq 30$~K in (Li$_2$Mn)$Ch$O to $\simeq 50$~K in (Li$_2$Fe)$Ch$O and $70-90$~K in (Li$_2$Co)$Ch$O. Except for $M$ = Co, the chalcogenide has no sizable effect on $T_{\rm N}$. We conclude significant magnetic coupling and short-range magnetic correlations at well above $T_{\rm N}$ which is in line with the observation of a broad electron spin resonance signal at room temperature. The actual ordering temperatures are strongly diminished by magnetic dilution. While structural parameters such as the tolerance factor and bonding angles do not strongly affect $T_{\rm N}$, a key parameter is the magnetic anisotropy of the transition metals.
