We performed a comprehensive study on structural, electrical, magnetic, and optical properties for iron-based ladder materials ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3(0\le x\le 1)$, which shows pressure-induced superconductivity in the vicinity of the Mott transition at $x=0$ and 1. We obtain a complete electronic phase diagram in a temperature-composition plane, which reveals that the magnetic ground state switches from the stripe-type to the block-type phase without any intermediate phase at $x=0.23$ with increasing $x$. This behavior is in sharp contrast to the filling controlled system ${\mathrm{Ba}}_{1-x}{\mathrm{Cs}}_x{\mathrm{Fe}}_2{\mathrm{Se}}_3$, in which a paramagnetic state down to the lowest temperature is realized between two magnetic ordered states. The structural transition, which is considered to be relevant to the orbital order, occurs far above the magnetic transition temperature. The magnetic and structural transition temperatures exhibit a similar composition dependence, indicating a close relationship between magnetic and orbital degrees of freedom. In addition, we found that charge dynamics are considerably influenced not only by the magnetic order but also by the structural change (orbital order) from the detailed measurements of electrical resistivity and optical conductivity spectra. We discuss the magnetism and orbital order by comparing the experimental results with the proposed theory based on the multiorbital Hubbard model. The relationship between the charge dynamics and the magnetic/orbital order is also discussed.

中文翻译：

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铁基梯形化合物BaFe2（S1-xSex）3的结构，电，磁和光学性质

我们对铁基梯子材料的结构，电，磁和光学性能进行了全面研究 ${\mathrm{钡铁}}_2{（{\mathrm{小号}}_{\mathrm{1个}-X}{硒}_X）}_3（0\le X\le \mathrm{1个}）$，这表明在Mott跃迁附近压力引起的超导 $X=0$ 1.我们在温度组成平面上获得了完整的电子相图，该图揭示了磁性基态从条状相转换为块状相，而在此没有任何中间相 $X=0.23$ 随着增加 $X$。这种行为与灌装控制系统形成鲜明对比${巴}_{\mathrm{1个}-X}{\mathrm{Cs}}_X{铁}_2{硒}_3$，其中在两个磁性有序状态之间实现了最低温度的顺磁性状态。被认为与轨道次序有关的结构转变发生在远高于磁转变温度的位置。磁性和结构转变温度表现出相似的成分依赖性，表明磁性和轨道自由度之间存在密切关系。此外，我们从电阻率和光导率谱的详细测量中发现，电荷动力学不仅受磁阶而且受结构变化（轨道阶）的影响很大。通过将实验结果与基于多轨道Hubbard模型的理论进行比较，我们讨论了磁场和轨道顺序。