High-Temperature Superconductivity in Lattice-Expanded C
            <sub>60</sub>

Schön, J. H.; Kloc, Ch.; Batlogg, B.

doi:10.1126/science.1064773

Cited by 155 publications

(128 citation statements)

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“…Therefore, we classify the molecular terms [26,27,28,29] by the symbol 2S+1 Γ, where 2S + 1 is the spin multiplicity and Γ is an irrep of I h . Thus, the molecular terms are 3 …”

Section: Methods Of Calculationmentioning

confidence: 99%

“…After almost ten years of intensive theoretical and experimental work, unexpected discoveries of ferromagnetic polymerized C 60 [1] as well as superconductivity in hole doped pristine C 60 [2] and in lattice-expanded C 60 [3] raise new questions about the electronic structure of the C 60 molecule and its molecular ions. Using the field-effect doping techniques, it has been shown that high transition temperatures are achieved for the case of three holes per the C 60 molecule [2], when many electron effects come into play.…”

Section: Introductionmentioning

confidence: 99%

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Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

Николаев

Michel

2002

The Journal of Chemical Physics

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Starting from a multipole expansion of intra-molecular Coulomb interactions, we present configuration interaction calculations of the molecular energy terms of the hole configurations (h + u ) m , m = 2 − 5, of C m+ 60 cations, of the electron configurations t n 1u , n = 2 − 4, of the C n− 60 anions, and of the exciton configurations (h + u t − 1u ), (h + u t − 1g ) of the neutral C60 molecule. The ground state of C 2− 60 is either 3 T1g or 1 Ag, depending on the energy separation between t1g and t1u levels. There are three close (∼0.03 eV) low lying triplets 3 T1g, 3 Gg, 3 T2g for C 2+ 60 , and three quartets 4 T1u, 4 Gu, 4 T2u for C 3+ 60 , which can be subjected to the Jahn-Teller effect. The number of low lying nearly degenerate states in largest for m = 3 holes. We have calculated the magnetic moments of the hole and electron configurations and found that they are independent of molecular orientation in respect to an external magnetic field. The coupling of spin and orbital momenta differs from the atomic case. We analyze the electronic dipolar transitions (t1u) 2 → t1ut1g and (t1u) 3 → (t1u) 2 t1g for C 2− 60 and C 3− 60 . Three optical absorption lines ( 3 T1g → 3 Hu, 3 T1u, 3 Au) are found for the ground level of C 2− 60 and only one line ( 4 Au → 4 T1g) for the ground state of C 3− 60 . We compare our results with the experimental data for C n− 60 in solutions and with earlier theoretical studies.

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“…Therefore, we classify the molecular terms [26,27,28,29] by the symbol 2S+1 Γ, where 2S + 1 is the spin multiplicity and Γ is an irrep of I h . Thus, the molecular terms are 3 …”

Section: Methods Of Calculationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

Николаев

Michel

2002

The Journal of Chemical Physics

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“…High level of chemical doping by acceptor intercalation was for long time unsuccessful in graphite as well as in C 60 since such compounds resulted unstable [13]. The recent discoveries of superconductivity at T c = 35 K in graphite-sulphur compounds [31] and at T c = 117 K in FET hole-doped fullerenes [2] could thus both arise from the unifying framework of the nonadiabatic superconductivity. We thus encourage renewed work along these lines.…”

mentioning

confidence: 99%

“…New techniques provide in fact the possibility to explore physical regimes that were previously inaccessible and superconducting materials which were often regarded as "conventional" BCS ones, as the fullerenes, have proven to be real high-T c compounds [2]. In this context the magnesium diboride MgB 2 , which was recently found to be superconductor with T c = 39 K [3], is a promising material.…”

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confidence: 99%

HighTcSuperconductivity inMgB2by Nonadiabatic Pairing

et al. 2002

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The evidence for the key role of the σ bands in the electronic properties of MgB2 points to the possibility of nonadiabatic effects in the superconductivity of these materials. These are governed by the small value of the Fermi energy due to the vicinity of the hole doping level to the top of the σ bands. We show that the nonadiabatic theory leads to a coherent interpretation of Tc = 39 K and the boron isotope coefficient αB = 0.30 without invoking very large couplings and it naturally explains the role of the disorder on Tc. It also leads to various specific predictions for the properties of MgB2 and for the material optimization of these type of compounds.

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“…On the other hand, more refined calculations of the fullerene-fullerene interaction yield results very close to those predicted through the Girifalco model [4,5], and a similar representation has been used for the description of other hollow nanoparticles as carbon onions, or metal dichalcogenides (also termed inorganic fullerenes) as GaAs and CdSe [6]. Moreover, a modification of the Girifalco model, suitable for the description of solid C 60 at low temperatures, has been recently proposed [7]; this development seems of particular interest since fullerites, doped with organic molecules and upon the injection of electron (or holes), exhibit a superconducting behavior up to T = 112 K [8]; an accurate description of such a simple model might prove useful for further studies on the lattice behavior upon impurity doping.…”

Section: Introductionmentioning

confidence: 99%

Free energy determination of phase coexistence in model C60: A comprehensive Monte Carlo study

Costa

Pellicane

Abramo

et al. 2003

The Journal of Chemical Physics

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The free energy of the solid and fluid phases of the Girifalco C60 model are determined through extensive Monte Carlo simulations. In this model the molecules interact through a spherical pair potential, characterized by a narrow and attractive well, adjacent to a harshly repulsive core. We have used the Widom test particle method and a mapping from an Einstein crystal, in order to estimate the absolute free energy in the fluid and solid phases, respectively; we have then determined the free energy along several isotherms, and the whole phase diagram, by means of standard thermodynamic integrations. The dependence of the simulation's results on the size of the sample is also monitored in a number of cases.We highlight how the interplay between the liquid-vapor and the liquid-solid coexistence conditions determines the existence of a narrow liquid pocket in the phase diagram, whose stability is assessed and confirmed in agreement with previous studies. In particular, the critical temperature follows closely an extended corresponding-states rule recently outlined by Noro and Frenkel [J. Chem. Phys. 113, 2941 (2000)].We discuss the emerging "energetic" properties of the system, which drive the phase behavior in systems interacting through short-range forces [A. A. Louis, Phil. Trans. R. Soc. A 359, 939 (2001)], in order to explain the discrepancy between the predictions of several structural indicators and the results of full free energy calculations, to locate the fluid phase boundaries.More generally, we aim to provide extended reference data for calculations of the free energy of the C60 fullerite in the low temperature regime, as for the determination of the phase diagram of higher order Cn>60 fullerenes and other fullerene-related materials, whose description is based on the same model adopted in this work.

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High-Temperature Superconductivity in Lattice-Expanded C ₆₀

Cited by 155 publications

References 15 publications

Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

HighTcSuperconductivity inMgB2by Nonadiabatic Pairing

Free energy determination of phase coexistence in model C60: A comprehensive Monte Carlo study

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High-Temperature Superconductivity in Lattice-Expanded C 60

Cited by 155 publications

References 15 publications

Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

Molecular terms, magnetic moments, and optical transitions of molecular ions C60m±

HighTcSuperconductivity inMgB2by Nonadiabatic Pairing

Free energy determination of phase coexistence in model C60: A comprehensive Monte Carlo study

Contact Info

Product

Resources

About

High-Temperature Superconductivity in Lattice-Expanded C ₆₀