标题： Ising自旋链磁体中高自旋和低自旋态的可视化 显示英文标题

标题： Visualization of Co-3d high- and low-spin states in an Ising spin chain magnet

摘要： 三价钴氧化物的性质主要受每个钴位点的六个 3d 电子自旋态的影响。高自旋 Co3+ 离子中，轨道角动量仅部分被淬灭，通常表现出显著的各向异性，为伊辛自旋系统提供了研究场所。然而，对其轨道态的实空间观测仍然有限。在这里，我们确定了伊辛自旋链磁体 Ca3Co2O6 中钴的 3d 自旋和轨道态，在该材料中高自旋态和低自旋态沿链交替出现。利用同步加速器 X 射线衍射和价电子密度（VED）分析，结合核心微分傅里叶合成（CDFS）方法，揭示了两个具有不同对称性的钴位点周围明显的各向异性 VED 分布。八面体钴位点周围的 VED 分布对应于低自旋态，而三方棱柱形钴位点表现出无法仅由晶体电场（CEF）解释的各向异性 VED。这种各向异性通过结合 CEF、自旋-轨道耦合以及现场 3d-4p 轨道杂化的模型更好地再现，这与表现出伊辛磁性的高自旋态一致。这些结果深入揭示了 Co-3d 态的性质，并强调了 CDFS 方法在探索量子材料相互作用中的实用性。 显示英文摘要

摘要： Properties of trivalent cobalt oxide compounds are largely influenced by the spin state of the six 3d electrons at each Co site. High-spin Co3+ ions, where orbital angular momentum is only partially quenched, often exhibit significant anisotropy, providing playgrounds for Ising spin systems. However, real-space observations of their orbital states have remained limited. Here, we determine the Co-3d spin and orbital states in an Ising spin chain magnet Ca3Co2O6, where high- and low-spin states alternate along the chain. Synchrotron X-ray diffraction and valence electron density (VED) analysis, utilizing the core differential Fourier synthesis (CDFS) method, reveal distinct anisotropic VED distributions around the two Co sites with different symmetries. The VED distribution around the octahedral Co site corresponds to a low-spin state, while the trigonal-prismatic Co site exhibits anisotropic VED that cannot be explained by the crystal electric field (CEF) alone. This anisotropy is better reproduced by a model incorporating CEF, spin-orbit coupling, and on-site 3d-4p orbital hybridization, consistent with a high-spin state exhibiting Ising magnetism. These results provide deeper insight into Co-3d states and highlight the CDFS method's utility in exploring interactions in quantum materials.