Magnetic-field penetration depth in K3C60 measured by muon spin relaxation

Uemura, Y. J.; Keren, Amit; Le, L. P.; Luke, G. M.; Sternlieb, B. J.; Wu, W. D.; Brewer, Jess H.; Whetten, Robert L.; Huang, Sampson C.; Lin, Sophia; Kaner, Richard B.; Diederich, François; Donovan, S.; Grüner, G.; Holczer, K.

doi:10.1038/352605a0

Cited by 222 publications

(89 citation statements)

References 14 publications

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“…Putting ξ GL = 30Å, which is reasonable in view of the results below, one obtains the values λ(0) = 2500Å for K 3 C 60 and 2600 and 3700Å for Rb 3 C 60 . The penetration depth has also been estimated from µSR with the results 4800Å for K 3 C 60 and 4200Å for Rb 3 C 60 (Uemura et al, 1991;, and from the optical conductivity with the result 8000Å for both K 3 C 60 and Rb 3 C 60 (Degiorgi et al, 1992) and from NMR data giving 6000Å for K 3 C 60 and 4600Å for Rb 3 C 60 . Uemura et al (1991) also deduced the temperature dependence of penetration depth λ(T ).…”

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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Section: Isotope Effectmentioning

confidence: 99%

Superconductivity in fullerides

1997

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“…After this processing, we produced a plot of T c versus T F first in 1991 [5]. Figure 2 shows the up-to-date version of this plot, including subsequent data from varous different superconductors [33,[35][36][37][38][39] The T B line represents the BE condensation temperature of an ideal Bose gas of boson mass 2m * and density n s /2. Although the actual superconducting T c of the cuprates are reduced by a factor 4-5 from T B , the trend of the underdoped cuprates is parallel to the T B line, suggesting that the linear trend can be deeply related to BE condensation.…”

Section: Plots Of Tc Vs Ns/m * and Tc Vs Tfmentioning

confidence: 99%

“…Although the actual superconducting T c of the cuprates are reduced by a factor 4-5 from T B , the trend of the underdoped cuprates is parallel to the T B line, suggesting that the linear trend can be deeply related to BE condensation. There seems to be an empirical upper limit of T c /T F shared not only by the cuprates but also by other strongly correlated systems, such as organic 2-d BEDT [37], Na x CoO 2 [39], and A 3 C 60 [35,36] systems. Figure 2 serves for classifying different superconductors between the limits of BE condensation with strong coupling (approaching towards the T B line) and BCS condensation with much smaller values of T c /T F .…”

Section: Plots Of Tc Vs Ns/m * and Tc Vs Tfmentioning

confidence: 99%

Condensation, excitation, pairing, and superfluid density in high-T_c superconductors: the magnetic resonance mode as a roton analogue and a possible spin-mediated pairing

Uemura¹

2004

J. Phys.: Condens. Matter

102

123

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To find out a primary determing factor of Tc and a pairing mechanism in high-Tc cuprates, we combine the muon spin relaxation results on ns/m * (superconducting carrier density / effective mass), accumulated over the last 15 years, with the results from neutron and Raman scattering, STM, specific heat, Nernst effect and ARPES measurements. We identify the neutron magnetic resonance mode as an analogue of roton minimum in the superfluid 4 He, and argue that ns/m * and the resonance mode energy ωres play a primary role in determining Tc in the underdoped region. We propose a picture that roton-like excitations in the cuprates appear as a coupled mode, which has the resonance mode for spin and charge responses at different momentum transfers but the same energy transfers, as detected respectively, by the neutron S=1 mode and the Raman S=0 A1g mode. We shall call this as the "hybrid spin/charge roton". After discussing the role of dimensionality in condensation, we propose a generic phase diagram of the cuprates with spatial phase separation in the overdoped region as a special case of the BE-BCS crossover conjecture where the superconducting coupling is lost rapidly in the overdoped region. Using a microscopic model of charge motion resonating with antiferomagnetic spin fluctuations, we propose a possibility that the hybrid spin/charge roton and higher-energy spin fluctuations mediate the superconducting pairing. In this model, the resonance modes can be viewed as a meson-analogue and the "dome" shape of the phase diagram can be understood as a natural consequence of departure from the competing Mott insulator ground state via carrier doping.

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“…217 ' 218 Future work is needed to clarify the experimental picture of the isotope effect in the M3C60 compounds. Also of significance to the pairing mechanism for superconductivity in the doped fullerenes is the muon spin resonance (/ASR) experiment which shows an isotropic superconducting gap, 220 as is also found in BCS superconductors.…”

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confidence: 99%

Fullerenes

1993

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A review of the structure and properties of fullerenes is presented. Emphasis is given to their behavior as molecular solids. The structure and property modifications produced by alkali-metal doping are summarized, including modification to the electronic structure, lattice modes, transport, and optical properties. Particular emphasis is given to the alkali-metal-doped fullerenes because of their importance as superconductors. A review of the structure and properties of fullerene-based graphene tubules is also given, including a model for their one-dimensional electronic band structure. Potential applications for fullerene-based materials are suggested.

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Magnetic-field penetration depth in K3C60 measured by muon spin relaxation

Cited by 222 publications

References 14 publications

Superconductivity in fullerides

Superconductivity in fullerides

Condensation, excitation, pairing, and superfluid density in high-T_c superconductors: the magnetic resonance mode as a roton analogue and a possible spin-mediated pairing

Fullerenes

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Magnetic-field penetration depth in K3C60 measured by muon spin relaxation

Cited by 222 publications

References 14 publications

Superconductivity in fullerides

Superconductivity in fullerides

Condensation, excitation, pairing, and superfluid density in high-Tc superconductors: the magnetic resonance mode as a roton analogue and a possible spin-mediated pairing

Fullerenes

Contact Info

Product

Resources

About

Condensation, excitation, pairing, and superfluid density in high-T_c superconductors: the magnetic resonance mode as a roton analogue and a possible spin-mediated pairing