Evidence of Strong Correlations and Coherence-Incoherence Crossover in the Iron Pnictide Superconductor KFe2As2

TitleEvidence of Strong Correlations and Coherence-Incoherence Crossover in the Iron Pnictide Superconductor KFe2As2
Publication TypeJournal Article
Year of Publication2013
AuthorsHardy F, Bohmer AE, Aoki D, Burger P, Wolf T, Schweiss P, Heid R, Adelmann P, Yao YX, Kotliar G, Schmalian J, Meingast C
Journal TitlePhysical Review Letters
Volume111
Pages027002
Date Published07
Type of ArticleArticle
ISBN Number0031-9007
Accession NumberWOS:000321752400034
Keywordschalcogenides, heat, transition
Abstract

Using resistivity, heat-capacity, thermal-expansion, and susceptibility measurements we study the normal-state behavior of KFe2As2. Both the Sommerfeld coefficient (gamma approximate to 103 mJ mol(-1) K-2) and the Pauli susceptibility (chi approximate to 4 x 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.

URL<Go to ISI>://WOS:000321752400034
DOI10.1103/PhysRevLett.111.027002