Isotope effect on superconductivity in Rb3C60

Ebbesen, Thomas W.; Tsai, Jung‐Hui; Tanigaki, Katsumi; Tabuchi, Junji; Shimakawa, Yuichi; Kubo, Yoshimi; Hirosawa, Ichiro; Мizuki, J.

doi:10.1038/355620a0

Cited by 107 publications

(17 citation statements)

References 13 publications

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“…To test whether either HeQh or HJTh is sufficient, we carried out the same calculations using only one coupling. (28)(29)(30). Including only JT with RSC = 0.5 A leads to T, = 1.5 K (which goes to zero for higher Rj) and a negative value of ac, also in disagreement with experiment (28)(29)(30); these results for JT alone differ from ref.…”

Section: Discussioncontrasting

confidence: 56%

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Mechanism of superconductivity in K3C60.

Chen

Goddard

1993

Proc. Natl. Acad. Sci. U.S.A.

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Section: Discussioncontrasting

confidence: 56%

“…Here we used the LDA results (27) A second significant test is the shift of T, with isotope substitution. Experiments lead to ac = 0.30 ± 0.06 for K3C60 (28) and ac = 0.37 + 0.05 for Rb3C60 (29) [an early report (30) of ac = 1.4 ± 0.5 may be inaccurate]. We recalculated all phonon states and A(w) for both 12C -* 13C and for 39K -+ 41K.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of superconductivity in K3C60.

Chen

Goddard

1993

Proc. Natl. Acad. Sci. U.S.A.

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“…A value of α which is larger than 0.5 is unusual, but it was also observed by three other groups. Ebbesen et al (1992a) obtained α = 1.4 ± 0.5 for Rb 3 C 60 (33% substitution), Zakhidov et al (1992) obtained α = (1.2 − 1.43) ± 0.2 for K 3 C 60 and α = (2 − 2.25) ± 0.25 for Rb 3 C 60 (60% substitution) and Auban-Senzier et al (1993) obtained α = 1.45 ± 0.3 for 82 % substitution. However, these results were observed for distributions of C 60 masses with essentially only one peak, while the α > 0.5 was obtained by Chen and Lieber (1993) for a two-peak distribution.…”

Section: Isotope Effectmentioning

confidence: 99%

Superconductivity in fullerides

1997

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Experimental studies of superconductivity properties of fullerides are briefly reviewed. Theoretical calculations of the electron-phonon coupling, in particular for the intramolecular phonons, are discussed extensively. The calculations are compared with coupling constants deduced from a number of different experimental techniques. It is discussed why the A 3 C 60 are not Mott-Hubbard insulators, in spite of the large Coulomb interaction. Estimates of the Coulomb pseudopotential µ * , describing the effect of the Coulomb repulsion on the superconductivity, as well as possible electronic mechanisms for the superconductivity are reviewed. The calculation of various properties within the Migdal-Eliashberg theory and attempts to go beyond this theory are described.

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“…According to the Bardeen-Cooper-Schrieffer (BCS) § We quote the exponent measured for 99 % 13 C-rich samples. The exponents obtained for the samples with incomplete substitution range from ∼ 0.3 to ∼ 2.1 [30,[75][76][77]. theory, it leads to the increase of T c [4,5].…”

Section: Evidences Of Phononsmentioning

confidence: 99%

Exotics-wave superconductivity in alkali-doped fullerides

Nomura

Sakai

Capone

et al. 2016

J. Phys.: Condens. Matter

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Alkali-doped fullerides (A3C60 with A = K, Rb, Cs) show a surprising phase diagram, in which a high transition-temperature (Tc) s-wave superconducting state emerges next to a Mott insulating phase as a function of the lattice spacing. This is in contrast with the common belief that Mott physics and phonon-driven s-wave superconductivity are incompatible, raising a fundamental question on the mechanism of the high-Tc superconductivity. This article reviews recent ab initio calculations, which have succeeded in reproducing comprehensively the experimental phase diagram with high accuracy and elucidated an unusual cooperation between the electron-phonon coupling and the electron-electron interactions leading to Mott localization to realize an unconventional s-wave superconductivity in the alkali-doped fullerides. A driving force behind the exotic physics is unusual intramolecular interactions, characterized by the coexistence of a strongly repulsive Coulomb interaction and a small effectively negative exchange interaction. This is realized by a subtle energy balance between the coupling with the Jahn-Teller phonons and Hund's coupling within the C60 molecule. The unusual form of the interaction leads to a formation of pairs of up- and down-spin electrons on the molecules, which enables the s-wave pairing. The emergent superconductivity crucially relies on the presence of the Jahn-Teller phonons, but surprisingly benefits from the strong correlations because the correlations suppress the kinetic energy of the electrons and help the formation of the electron pairs, in agreement with previous model calculations. This confirms that the alkali-doped fullerides are a new type of unconventional superconductors, where the unusual synergy between the phonons and Coulomb interactions drives the high-Tc superconductivity.

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Isotope effect on superconductivity in Rb3C60

Cited by 107 publications

References 13 publications

Mechanism of superconductivity in K3C60.

Mechanism of superconductivity in K3C60.

Superconductivity in fullerides

Exotics-wave superconductivity in alkali-doped fullerides

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