Petersen Thorben, Bhattacharyya Pritam, Rößler Ulrich K, Hozoi Liviu
Institute for Theoretical Solid State Physics, Leibniz IFW Dresden, Helmholtzstraße 20, Dresden, D-01069, Germany.
Nat Commun. 2023 Aug 26;14(1):5218. doi: 10.1038/s41467-023-40811-y.
The valence electronic structure of magnetic centers is one of the factors that determines the characteristics of a magnet. This may refer to orbital degeneracy, as for j = 1/2 Kitaev magnets, or near-degeneracy, e.g., involving the third and fourth shells in cuprate superconductors. Here we explore the inner structure of magnetic moments in group-5 lacunar spinels, fascinating materials featuring multisite magnetic units in the form of tetrahedral tetramers. Our quantum chemical analysis reveals a very colorful landscape, much richer than the single-electron, single-configuration description applied so far to all group-5 GaMX chalcogenides, and clarifies the basic multiorbital correlations on M tetrahedral clusters: while for V strong correlations yield a wave-function that can be well described in terms of four VVVV resonant valence structures, for Nb and Ta a picture of dressed molecular-orbital j = 3/2 entities is more appropriate. These internal degrees of freedom likely shape vibronic couplings, phase transitions, and the magneto-electric properties in each of these systems.
磁性中心的价电子结构是决定磁体特性的因素之一。这可能涉及轨道简并，如对于j = 1/2的 Kitaev 磁体，或近简并，例如涉及铜酸盐超导体中的第三和第四壳层。在这里，我们探索了第5族缺位尖晶石中磁矩的内部结构，这是一类迷人的材料，其具有以四面体四聚体形式存在的多位点磁性单元。我们的量子化学分析揭示了一幅非常丰富多彩的图景，远比迄今为止应用于所有第5族 GaMX 硫族化物的单电子、单构型描述丰富得多，并阐明了M四面体簇上的基本多轨道相关性：对于V，强相关性产生一种波函数，可用四个 VVVV 共振价键结构很好地描述；对于 Nb 和 Ta，一种修饰分子轨道j = 3/2实体的图景更为合适。这些内部自由度可能塑造了每个系统中的振动电子耦合、相变和磁电性质。
