Alkali-doped fullerides have attracted strong interest since their production became possible about fifteen years ago. This book presents recent work which may solve intriguing problems arising from a variety of remarkable properties. For example, these solids are superconductors with high transition temperatures, although the similarity between the electronic and phonon energy scales should suppress superconductivity. Moreover, the Ioffe-Regel condition for electrical conductivity is strongly violated. The book shows why superconductivity is nevertheless possible, owing to a local pairing mechanism. The Ioffe-Regel condition is derived quantum-mechanically, and it is explained why the underlying assumptions are violated for fullerides and high-Tc cuprates, for example. The book treats electronic and transport properties, reviewing theoretical and experimental results. It focuses on superconductivity, electrical conductivity and metal-insulator transitions, emphasizing the electron-electron and electron-phonon interactions as well as the Jahn-Teller effect.

Alkali-doped fullerides have attracted strong interest since their production became possible about fifteen years ago. This book presents recent work which may solve intriguing problems arising from a variety of remarkable properties. For example, these solids are superconductors with high transition temperatures, although the similarity between the electronic and phonon energy scales should suppress superconductivity. Moreover, the IoffeOCoRegel condition for electrical conductivity is strongly violated. The book shows why superconductivity is nevertheless possible, owing to a local pairing mechanism. The IoffeOCoRegel condition is derived quantum-mechanically, and it is explained why the underlying assumptions are violated for fullerides and high- T c cuprates, for example. The book treats electronic and transport properties, reviewing theoretical and experimental results. It focuses on superconductivity, electrical conductivity and metalOCoinsulator transitions, emphasizing the electronOCoelectron and electronOCophonon interactions as well as the JahnOCoTeller effect. Contents: Structural Properties; Models and Parameters; Phonons and ElectronOCoPhonon Coupling Strength; Interacting ElectronOCoPhonon System; Electronic Structure; Plasmons; MetalOCoInsulator Transition; Electrical Resistivity; Superconductivity. Readership: Graduate students and researchers in condensed matter physics."

This book covers high-transition temperature (Tc) s-wave superconductivity and the neighboring Mott insulating phase in alkali-doped fullerides. The author presents (1) a unified theoretical description of the phase diagram and (2) a nonempirical calculation of Tc. For these purposes, the author employs an extension of the DFT+DMFT (density-functional theory + dynamical mean-field theory). He constructs a realistic electron–phonon-coupled Hamiltonian with a newly formulated downfolding method. The Hamiltonian is analyzed by means of the extended DMFT. A notable aspect of the approach is that it requires only the crystal structure as a priori knowledge. Remarkably, the nonempirical calculation achieves for the first time a quantitative reproduction of the experimental phase diagram including the superconductivity and the Mott phase. The calculated Tc agrees well with the experimental data, with the difference within 10 K. The book provides details of the computational scheme, which can also be applied to other superconductors and other phonon-related topics. The author clearly describes a superconducting mechanism where the Coulomb and electron–phonon interactions show an unusual cooperation in the superconductivity thanks to the Jahn–Teller nature of the phonons.

Researchers at AT and T Bell Laboratories reported the discovery of superconductivity at 18 K in a potassium-doped fullerene solid, KxC60. This marked a major turning point in the young history of the C60 molecule 'buckminsterfullerene: from a hypothetical molecular (1085), to small-scale (mg) production of crystalline powders (1988), to large-scale synthesis (1990), to a material with the highest transition temperature of any molecular superconductor. This history represents only one of many research lines. Concurrently with the work at AT and T on partial doping, researchers at the Laboratory for Research on the Structure of Matter at the University of Pennsylvania were doping solid C60 to saturation with potassium. The resulting pure phase, K6C60, was characterized by x-ray diffraction in April 1991: the lattice was body-centered cubic, with the C60 molecules essentially undistorted, orientationally ordered, and each surrounded by a cage of 24 K atoms. Nothing was known about the electronic structure at this early stage.