Related papers: Do the A4c60 Fullerides Have a Broken-Symmetry Gro…
Metallic K3C60 shows pronounced structure and a sharp Fermi edge in integrated photoemission spectra (PES) while the insulating K4C60 and K6C60 phases display only a broad structureless peak. We find that both types of spectra can be…
Li4C60, one of the best representatives of lithium intercalated fullerides, features a novel type of 2D polymerization. Extensive investigations, including laboratory x-ray and synchrotron radiation diffraction, 13C NMR, MAS and Raman…
The restoration of metallicity in the high-temperature, cubic phase of Li4C60 represents a remarkable feature for a member of the A4C60 family (A = alkali metal), invariably found to be insulators. Structural and resonance technique…
Electron Spin Resonance and optical reflectivity measurements demonstrate a metal-insulator transition in Na_2CsC_60 as the system passes from the low temperature simple cubic to the high temperature {\it fcc} structure above 300 K. The…
The low-temperature structure of A1C60 (A=K, Rb) is an ordered array of polymerized C60 chains, with magnetic properties that suggest a non-metallic ground state. We study the paramagnetic state of this phase using first-principles…
The low-temperature structure of A1C60 (A=K, Rb) is an ordered array of polymerized C60 chains, with magnetic properties that suggest a non-metallic ground state. We study the paramagnetic state of this phase using first-principles…
We present a detailed NMR study of simple cubic CsC60, the only metallic cubic fullerides known so far besides A3C60. 133Cs NMR signals the presence of about 12 to 15% of ``anomalous'' C60 balls, characterized by a 15 meV gap. We present…
A singular evolution toward an insulating phase, shown by 23Na and 13C NMR, has been observed in the superconducting fullerides (NH3)xNaK2C60 for x>1. Unlike most common cases, this insulating phase is non magnetic and 13C spin lattice…
A novel fulleride Sm6C60 has been synthesized using high temperature solid state reaction. The Rietveld refinement on high resolution synchrotron X-ray powder diffraction data shows that Sm6C60 is isostructural with body-centered cubic…
Alkali-doped fullerides A$_n$C$_{60}$ show a remarkably wide range of electronic phases in function of A= Li, Na, K, Rb, Cs and the degree of doping, $n=1-5$. While the presence of strong electron correlations is well established, recent…
The recently discovered structural transition in polymerized KC60 at about 50 K results in a doubling of the unit cell volume and accompanies the metal-insulator transition. Here we show that the (a+c,b,a-c) superstructure results from…
We present an NMR study of Na2C60 and K4C60, two compounds that are related by electron-hole symmetry in the C60 triply degenerate conduction band. In both systems, it is known that NMR spin-lattice relaxation rate (1/T1) measurements…
133Cs and 13C-NMR have been used to study the electronic properties of the polymerized phase of CsC60 at ambient and under hydrostatic pressure. The salient result of this study is the finding of fluctuations in the local field at 133Cs…
We present a study on the structural, spectroscopic, conducting and magnetic properties of Mg5C60, a two dimensional (2D) fulleride polymer. The polymer phase is stable up to the exceptionally high temperature of 823 K. Infrared and Raman…
We review current theoretical and experimental efforts to identify a novel class of intermetallic 4f and 5f orbital materials in which strong interactions between itinerant and predominately localized degrees of freedom gives rise to a bulk…
An effective-medium theory for studying the electronic structure of the orientationally disordered A3C60 fullerides is developed and applied to study various normal-state properties. The theory is based on a cluster-Bethe-lattice method in…
C60 fullerides are uniquely flexible molecular materials that exhibit a rich variety of behavior, including superconductivity and magnetism in bulk compounds, novel electronic and orientational phases in thin films, and quantum transport in…
We review some theoretical aspects connected with the interplay of strong electron correlations and vibron phenomena in negative fullerene ions and in solid fulleride conductors, superconductors and insulators. The first part covers…
We study metallic behavior and superconductivity in C$_{60}$ materials in terms of a tight binding model characterized by an intramolecular, nonretarded attraction. It was shown previously that, at intermediate coupling, the model possesees…
Fullerene solids doped with alkali metals (A$_3$C$_{60}$, A = K, Rb, Cs) exhibit a superconducting transition temperature ($T_c$) as high as 40 K, and their unconventional superconducting properties have been a subject of debate. With…