Imaging orbital-selective quasiparticles in the Hund’s metal state of FeSe

A. Kostin, P. O. Sprau, A. Kreisel, Yi Xue Chong, A. E. Böhmer, P. C. Canfield, P. J. Hirschfeld, B. M. Andersen, J. C. Séamus Davis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


Strong electronic correlations, emerging from the parent Mott insulator phase, are key to copper-based high-temperature superconductivity. By contrast, the parent phase of an iron-based high-temperature superconductor is never a correlated insulator. However, this distinction may be deceptive because Fe has five actived d orbitals while Cu has only one. In theory, such orbital multiplicity can generate a Hund’s metal state, in which alignment of the Fe spins suppresses inter-orbital fluctuations, producing orbitally selective strong correlations. The spectral weights Zm of quasiparticles associated with different Fe orbitals m should then be radically different. Here we use quasiparticle scattering interference resolved by orbital content to explore these predictions in FeSe. Signatures of strong, orbitally selective differences of quasiparticle Zm appear on all detectable bands over a wide energy range. Further, the quasiparticle interference amplitudes reveal that Zx y< Zx z≪ Zy z, consistent with earlier orbital-selective Cooper pairing studies. Thus, orbital-selective strong correlations dominate the parent state of iron-based high-temperature superconductivity in FeSe.

Original languageEnglish
Pages (from-to)869–874
JournalNature Materials
Issue number10
Early online date3 Sept 2018
Publication statusPublished - Oct 2018


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