title: Absence of metallicity in K-doped picene: importance of electronic correlations.
abstract: Potassium-doped picene (K(x)picene) has recently been reported to be a superconductor at x=3 with critical temperatures up to 18 K. Here we study the electronic structure of K-doped picene films by photoelectron spectroscopy and ab initio density functional theory combined with dynamical mean-field theory (DFT+DMFT). Experimentally we observe that, except for spurious spectral weight due to the lack of a homogeneous chemical potential at low K concentrations (x≈1), the spectra always display a finite energy gap. This result is supported by our DFT+DMFT calculations which provide clear evidence that K(x)picene is a Mott insulator for integer doping concentrations x=1, 2, and 3. We discuss various scenarios to understand the discrepancies with previous reports of superconductivity and metallic behavior.
authors.affiliation: Physikalisches Institut, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ruff
authors.forename: Michael
authors.initials: M
authors.lastname: Sing
authors.forename: Ralph
authors.initials: R
authors.lastname: Claessen
authors.forename: Hunpyo
authors.initials: H
authors.lastname: Lee
authors.forename: Milan
authors.initials: M
authors.lastname: Tomić
authors.forename: Harald O
authors.initials: HO
authors.lastname: Jeschke
authors.forename: Roser
authors.initials: R
authors.lastname: Valentí