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DOE OSTI · 3018687

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

Chang, Ming-Hua [The Pennsylvania State University, University Park, PA (United States)]·Backes, Steffen [RIKEN iTHEMS, Saitama (Japan); RIKEN, Saitama (Japan)] (ORCID:0000000277617098)·Lu, Donghui [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000297080443)·Gauthier, Nicolas [Institut National de la Recherche Scientifique—Energie Matériaux Télécommunications, Varennes, QC (Canada)] (ORCID:000000016147243X)·Hashimoto, Makoto [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000316898997)·Chen, Guan-Yu [Nanjing University (China)]·Wen, Hai-Hu [Nanjing University (China)] (ORCID:0000000300931625)·Mo, Sung-Kwan [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000307118514)·Shen, Zhi-Xun [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford University, CA (United States)] (ORCID:0000000214540281)·Valentí, Roser [Goethe-Universität Frankfurt (Germany)] (ORCID:0000000304971165)·Pfau, Heike [The Pennsylvania State University, University Park, PA (United States)] (ORCID:0000000165794188)
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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 RbFe 2 As 2 . We observe that the emergence of low-energy Fe 3d xy 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.

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Chang, Ming-Hua [The Pennsylvania State University, University Park, PA (United States)], Backes, Steffen [RIKEN iTHEMS, Saitama (Japan); RIKEN, Saitama (Japan)] (ORCID:0000000277617098), Lu, Donghui [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000297080443), Gauthier, Nicolas [Institut National de la Recherche Scientifique—Energie Matériaux Télécommunications, Varennes, QC (Canada)] (ORCID:000000016147243X), Hashimoto, Makoto [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)] (ORCID:0000000316898997), Chen, Guan-Yu [Nanjing University (China)], Wen, Hai-Hu [Nanjing University (China)] (ORCID:0000000300931625), Mo, Sung-Kwan [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000307118514), Shen, Zhi-Xun [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford University, CA (United States)] (ORCID:0000000214540281), Valentí, Roser [Goethe-Universität Frankfurt (Germany)] (ORCID:0000000304971165), Pfau, Heike [The Pennsylvania State University, University Park, PA (United States)] (ORCID:0000000165794188). 2025-07-22. Observation of two cascading screening processes in an iron-based superconductor. https://doi.org/10.1038/s43246-025-00881-5

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