Spin alignment of extra electrons in K-phenanthrene clusters taken from the crystalline tripotassium-intercalated phenanthrene structure

Vergés, J. A.; Andrés, Pedro; San‐Fabián, Emilio; Chiappe, G.; Louis, E.; Guijarro, Albert

doi:10.1103/physrevb.85.165102

Cited by 9 publications

(11 citation statements)

References 37 publications

(40 reference statements)

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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%

“…Although our method is applied to a model Hamiltonian and a purely numerical algorithm is used for the selection of configurations, we believe that it shares some similarities with a well documented set of wise criteria of CI selection used for ab initio calculations [34]. Further details on the whole Lanczos procedure can be found in recent papers [16,35]. …”

Section: B Two-band Modelmentioning

confidence: 99%

“…This image supports a conducting system that becomes superconducting when the temperature decreases sufficiently. On the other hand, some papers have pointed to a magnetic character of the last bands that invalidates the naive picture of independent electrons [9,11,15,16].…”

Section: Introductionmentioning

confidence: 99%

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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%

Section: B Two-band Modelmentioning

confidence: 99%

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Role of potassium orbitals in the metallic behavior ofK3picene

et al. 2014

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“…The mean-field result is improved using a configuration interaction scheme within a wisely chosen subspace. 19 Further technical details regarding both quantum chemistry computation and the numerical solution of the many-body PPP model are given in the next sections.…”

Section: Methods and Numerical Proceduresmentioning

confidence: 99%

Exponential decay of spin-spin correlation between distant defect states produced by contour hydrogenation of polycyclic aromatic hydrocarbon molecules

et al. 2013

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The first few low-lying spin states of alternant polycyclic aromatic hydrocarbon (PAH) molecules of several shapes showing defect states induced by contour hydrogenation have been studied both by ab initio methods and by a precise numerical solution of Pariser-Parr-Pople (PPP) interacting model. In accordance with Lieb's theorem, the ground state shows a spin multiplicity equal to one for balanced molecules, and it gets larger values for imbalanced molecules (that is, when the number of π electrons on both subsets is not equal). Furthermore, we find a systematic decrease of the singlet-triplet splitting as a function of the distance between defects, regardless of whether the ground state is singlet or triplet. For example, a splitting smaller than 0.001 eV is obtained for a medium size C 46 H 28 PAH molecule (di-hydrogenated [11]phenacene) showing a singlet ground state. We conclude that π electrons unbound by lattice defects tend to remain localized and unpaired even when long-range Coulomb interaction is taken into account. Therefore they show a biradical character (polyradical character for more than two defects) and should be studied as two or more local doublets. The implications for electron transport are potentially important since these unpaired electrons can trap traveling electrons or simply flip their spin at a very small energy cost.

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“…In the multiconfigurational Lanczos (MCL) calculation [40,41] the system is described by the same tight-bindingbased Hamiltonian discussed before. The process requires the definition of a subsystem, a cluster of an arbitrary number of M sites that includes the DQD, the NILC, and a portion of the connecting leads.…”

Section: B Multiconfigurational Lanczosmentioning

confidence: 99%

Transport across two interacting quantum dots: Bulk Kondo, Kondo box, and molecular regimes

et al. 2014

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We analyze the transport properties of a double quantum dot device with both dots coupled to perfect conducting leads and to a finite chain of N noninteracting sites connecting both of them. The interdot chain strongly influences the transport across the system and the local density of states of the dots. We study the case of a small number of sites, so that Kondo box effects are present, varying the coupling between the dots and the chain. For odd N and small coupling between the interdot chain and the dots, a state with two coexisting Kondo regimes develops: the bulk Kondo due to the quantum dots connected to leads and the one produced by the screening of the quantum dot spins by the spin in the finite chain at the Fermi level. As the coupling to the interdot chain increases, there is a crossover to a molecular Kondo effect, due to the screening of the molecule (formed by the finite chain and the quantum dots) spin by the leads. For even N the two Kondo temperatures regime does not develop and the physics is dominated by the usual competition between Kondo and antiferromagnetism between the quantum dots. We finally study how the transport properties are affected as N is increased. For the study we used exact multiconfigurational Lanczos calculations and finite-U slave-boson mean-field theory at T = 0. The results obtained with both methods describe qualitatively and also quantitatively the same physics.

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Spin alignment of extra electrons in K-phenanthrene clusters taken from the crystalline tripotassium-intercalated phenanthrene structure

Cited by 9 publications

References 37 publications

Role of potassium orbitals in the metallic behavior ofK3picene

Role of potassium orbitals in the metallic behavior ofK3picene

Exponential decay of spin-spin correlation between distant defect states produced by contour hydrogenation of polycyclic aromatic hydrocarbon molecules

Transport across two interacting quantum dots: Bulk Kondo, Kondo box, and molecular regimes

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