Strong Intramolecular Electron-Phonon Coupling in the Negatively Charged Aromatic Superconductor Picene

Kato, Takashi; Kambe, Takashi; Kubozono, Yoshihiro

doi:10.1103/physrevlett.107.077001

Cited by 73 publications

(94 citation statements)

References 32 publications

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“…In this context both many-body effects and electron-phonon interactions would be important [9,[14][15][16][37][38][39][40]. Finally, let us remind one that after the seminal work by Mitsuhashi et al [1] showing the existence of superconducting phases for potassium-intercalated picene, additional experimental evidence points to a metallic behavior of K 3 picene.…”

Section: Discussionmentioning

confidence: 99%

Role of potassium orbitals in the metallic behavior ofK3picene

et al. 2014

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Detailed electronic structure calculations of picene clusters doped by potassium modeling the crystalline K 3 picene structure show that while two electrons are completely transferred from potassium atoms to the lowest-energy unoccupied molecular orbital of pristine picene, the third one remains closely attached to both material components. Multiconfigurational analysis is necessary to show that many structures of almost degenerate total energies compete to define the cluster ground state. Our results prove that the 4s orbital of potassium should be included in any interaction model describing the material. We propose a quarter-filled two-orbital model as the most simple model capable of describing the electronic structure of K-intercalated picene. Precise solutions obtained by a development of the Lanczos method show low-energy electronic excitations involving orbitals located at different positions. Consequently, metallic transport is possible in spite of the clear dominance of interaction over hopping.

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Section: Discussionmentioning

confidence: 99%

Role of potassium orbitals in the metallic behavior ofK3picene

et al. 2014

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“…Finally let us discuss the possible relevance of these results for organic superconductors, such as alkali-doped fullerides and aromatic superconductors. [4][5][6] In these molecular solids, the characteristic frequency of intramolecular phonons is reported to be not larger than but comparable to the electronic bandwidth or the inverse of the density of states at the Fermi level. What we have found here is that the effective static model is qualitatively reliable even for ω 0 ≃ t = W/4.…”

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confidence: 92%

Ordered phases in the Holstein-Hubbard model: Interplay of strong Coulomb interaction and electron-phonon coupling

et al. 2013

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We study the Holstein-Hubbard model at half filling to explore ordered phases including superconductivity (SC), antiferromagnetism (AF), and charge order (CO) in situations where the electron-electron and electron-phonon interactions are strong (∼ electronic bandwidth). The model is solved in the dynamical mean-field approximation using a continuous-time quantum Monte Carlo impurity solver. We determine the superconducting transition temperature (Tc) and the SC order parameter and show that the phonon-induced retardation or the strong Coulomb interaction leads to a significant reduction and shift of the Tc dome if one interprets the system as having an effective static interaction U eff given by the Hubbard U reduced by the phonon-mediated attraction in the static limit. This behavior is analyzed by comparison to an effective static model in the polaron representation with a reduced bandwidth. We also determine the finite-temperature phase diagram including AF and CO. In the moderate-coupling regime, there is a hysteretic region of AF and CO around U eff = 0, while the two phases are separated by a paramagnetic metal in the weak-coupling regime and a paramagnetic insulator in the strong coupling regime.

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“…In a simple one-electron picture, K-intercalation is expected to induce electron transfer into the lowest unoccupied molecular orbital (LUMO) of picene, leading to a partially filled, i.e., metallic conduction band which at low temperatures would host the superconductivity, as suggested in various theoretical studies [9,[11][12][13][14][15][16][17][18][19]. However, such calculations include electronic correlations only at the level of the exchange-correlation functional considered within density functional theory (DFT) and neglect electron-phonon interactions.…”

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confidence: 99%

Absence of Metallicity in K-doped Picene: Importance of Electronic Correlations

et al. 2013

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Potassium-doped picene (Kxpicene) 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 Kxpicene 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.

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Strong Intramolecular Electron-Phonon Coupling in the Negatively Charged Aromatic Superconductor Picene

Cited by 73 publications

References 32 publications

Role of potassium orbitals in the metallic behavior ofK3picene

Role of potassium orbitals in the metallic behavior ofK3picene

Ordered phases in the Holstein-Hubbard model: Interplay of strong Coulomb interaction and electron-phonon coupling

Absence of Metallicity in K-doped Picene: Importance of Electronic Correlations

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