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DOE OSTI · 2571911

Orbital inversion and emergent lattice dynamics in infinite layer CaCoO 2

Jost, Daniel [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000173277789)·Lomeli, Eder G. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)]·Kim, Woo Jin [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)]·Been, Emily M. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000222467336)·Rossi, Matteo [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000242540713)·Agrestini, Stefano [Diamond Light Source, Harwell Campus, Didcot (United Kingdom)] (ORCID:000000023625880X)·Zhou, Ke-Jin [Univ. of Science and Technology of China, Hefei (China); Diamond Light Source, Harwell Campus, Didcot (United Kingdom)] (ORCID:0000000192930595)·Jia, Chunjing [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)]·Moritz, Brian [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)]·Shen, Zhi-Xun [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000214540281)·Hwang, Harold Y. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000292303214)·Devereaux, Thomas P. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000180729237)·Lee, Wei-Sheng [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000176770421)
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Abstract

The layered cobaltate CaCoO 2 exhibits a unique herringbone-like structure. Serving as a potential prototype for a new class of complex lattice patterns, we study the properties of CaCoO 2 using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). Our results reveal a significant inter-plane hybridization between the Ca 4s- and Co 3d- orbitals, leading to an inversion of the textbook orbital occupation of a square planar geometry. Further, our RIXS data reveal a strong low energy mode, with anomalous intensity modulations as a function of momentum transfer close to a quasi-static response. These findings indicate that the newly discovered herringbone structure exhibited in CaCoO 2 may serve as a promising laboratory for the design of materials having strong electronic, orbital and lattice correlations.

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Jost, Daniel [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000173277789), Lomeli, Eder G. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)], Kim, Woo Jin [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)], Been, Emily M. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000222467336), Rossi, Matteo [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000242540713), Agrestini, Stefano [Diamond Light Source, Harwell Campus, Didcot (United Kingdom)] (ORCID:000000023625880X), Zhou, Ke-Jin [Univ. of Science and Technology of China, Hefei (China); Diamond Light Source, Harwell Campus, Didcot (United Kingdom)] (ORCID:0000000192930595), Jia, Chunjing [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)], Moritz, Brian [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)], Shen, Zhi-Xun [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000214540281), Hwang, Harold Y. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000292303214), Devereaux, Thomas P. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)] (ORCID:0000000180729237), Lee, Wei-Sheng [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000176770421). 2025-06-16. Orbital inversion and emergent lattice dynamics in infinite layer CaCoO 2. https://doi.org/10.1038/s41535-025-00778-z

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