Evidence of strong correlations and coherence-incoherence crossover in the iron pnictide superconductor KFe2As2

F. Hardy, A. E. Böhmer, D. Aoki, P. Burger, T. Wolf, P. Schweiss, R. Heid, P. Adelmann, Y. X. Yao, G. Kotliar, J. Schmalian, C. Meingast

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Abstract

Using resistivity, heat-capacity, thermal-expansion, and susceptibility measurements we study the normal-state behavior of KFe2As 2. Both the Sommerfeld coefficient (γ≈103 mJ mol -1 K-2) and the Pauli susceptibility (χ≈4× 10-4) are strongly enhanced, which confirm the existence of heavy quasiparticles inferred from previous de Haas-van Alphen and angle-resolved photoemission spectroscopy experiments. We discuss this large enhancement using a Gutzwiller slave-boson mean-field calculation, which shows the proximity of KFe2As2 to an orbital-selective Mott transition. The temperature dependence of the magnetic susceptibility and the thermal expansion provide strong experimental evidence for the existence of a coherence- incoherence crossover, similar to what is found in heavy fermion and ruthenate compounds, due to Hund's coupling between orbitals.

Original languageEnglish
Article number027002
JournalPhysical review letters
Volume111
Issue number2
DOIs
Publication statusPublished - 2013 Jul 9

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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