Observation of two cascading screening processes in an iron-based superconductor

Abstract Understanding how renormalized quasiparticles emerge in strongly correlated electron materials provides a challenge for both experiment and theory. It has been predicted that distinctive spin and orbital screening mechanisms drive this process in multiorbital materials with strong Coulomb a...

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Main Authors: Ming-Hua Chang, Steffen Backes, Donghui Lu, Nicolas Gauthier, Makoto Hashimoto, Guan-Yu Chen, Hai-Hu Wen, Sung-Kwan Mo, Zhi-Xun Shen, Roser Valentí, Heike Pfau
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Communications Materials
Online Access:https://doi.org/10.1038/s43246-025-00881-5
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Summary:Abstract Understanding how renormalized quasiparticles emerge in strongly correlated electron materials provides a challenge for both experiment and theory. It has been predicted that distinctive spin and orbital screening mechanisms drive this process in multiorbital materials with strong Coulomb and Hund’s interactions. Here, we provide the experimental evidence of both mechanisms from angle-resolved photoemission spectroscopy on RbFe2As2. We observe that the emergence of low-energy Fe 3d x y quasiparticles below 90K coincides with spin screening. A second process changes the spectral weight at high energies up to room temperature. Supported by theoretical calculations we attribute it to orbital screening of Fe 3d atomic excitations. These two cascading screening processes drive the temperature evolution from a bad metal to a correlated Fermi liquid.
ISSN:2662-4443