Year: 2026
Type: article
Abstract: High-spin Co 3+ ions can retain a finite orbital contribution and exhibit pronounced magnetic anisotropy, providing model systems for Ising magnetism. However, direct real-space observations of their orbital states remain limited. Here, we visualize the site-dependent Co 3d electronic states in the Ising-chain magnet Ca 3 Co 2 O 6 , which contains crystallographically inequivalent high-spin and low-spin Co 3+ sites, using synchrotron X-ray diffraction and valence electron density (VED) analysis based on core differential Fourier synthesis. The octahedral Co site exhibits a VED distribution consistent with a low-spin state, whereas the trigonal-prismatic Co site shows pronounced anisotropy that cannot be reproduced by crystal electric field (CEF) effects alone. A wavefunction analysis incorporating CEF effects, spin–orbit coupling, and ligand-mediated Co 3d–O 2p–Co 4p hybridization reproduces the observed VED anisotropy. These results establish a site-selective real-space picture of the Co electronic states and demonstrate the capability of VED analysis to probe local orbital states and orbital hybridization in quantum materials.
Authors: Kamini Gautam, Shunsuke Kitou, Yuiga Nakamura, Norimasa Sasabe, Arvind Kumar Yogi, Dinesh Kumar Shukla, Yuichi Yamasaki, Taka-hisa Arima
Institutions: RIKEN Center for Emergent Matter Science, The University of Tokyo, SPring-8, Japan Synchrotron Radiation Research Institute, National Institute for Materials Science, UGC DAE Consortium for Scientific Research, Tohoku University, International Center for Synchrotron Radiation Innovation Smart, Tohoku University
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4414590280