Vacancy‐ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of Ru^IV halides are presented; A₂RuCl₆ and A₂RuBr₆, where A is K, NH₄, Rb or Cs. We show that the optical properties and spin‐orbit coupling (SOC) behavior can be tuned through changing the A cation and the halide. Within a series, the energy of the ligand‐to‐metal charge transfer increases as the unit cell expands with the larger A cation, and the band gaps are higher for the respective chlorides than for the bromides. The magnetic moments of the systems are temperature dependent due to a non‐magnetic ground state with J_eff=0 caused by SOC. Ru‐X covalency, and consequently, the delocalization of metal d‐electrons, result in systematic trends of the SOC constants due to variations in the A cation and the halide anion.

中文翻译：

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空位有序的卤化钙钛矿中自旋轨道耦合和电荷转移的化学控制

空位排序的钙钛矿由于其化学多样性和有趣的光电特性而备受关注。为了理解这些化合物的光学和磁性，提出了两个系列的Ru ^IV卤化物。A ₂ RuCl ₆和A ₂ RuBr ₆，其中A为K，NH ₄，Rb或Cs。我们表明，可以通过改变A阳离子和卤化物来调节光学性质和自旋轨道耦合（SOC）行为。在一个系列中，配体到金属的电荷转移能量随着晶胞的扩大而增加，而更大的A离子，并且相应的氯化物的带隙高于溴化物。由于SOC导致J _eff = 0的非磁性基态，系统的磁矩与温度有关。由于A阳离子和卤化物阴离子的变化，Ru‐ X的共价关系以及金属d电子的离域化导致SOC常数的系统趋势。