K3C60

K3C60
Name	K3C60
Formula	K3C60

K3C60 K3C60 is an alkali-doped fulleride that attracted attention after reports of superconductivity and rich correlated-electron behavior; it sits at the intersection of research on Buckminster Fuller, Richard Smalley, Harold Kroto, Robert Curl, Alexey Abrikosov, and experimental groups at institutions such as Bell Labs, IBM, MIT, Harvard University. The compound links themes from studies of fullerene chemistry, high-temperature superconductor research exemplified by Bednorz and Müller, and condensed-matter work at laboratories including Max Planck Society and Los Alamos National Laboratory.

Introduction

K3C60 is a stoichiometric intercalation solid formed by three potassium atoms per molecule of the spherical polycarbon C60 cluster; early reports tied it to breakthroughs by researchers associated with Rice University, University of Sussex, University of Cambridge, Stanford University, and ETH Zurich. The system became a flagship material in comparisons with cuprate superconductors studied by teams at Bell Labs, IBM Research, Columbia University, University of Tokyo, and University of California, Berkeley, and it spurred theoretical work by figures linked to Princeton University, École Normale Supérieure, and Cambridge University.

Crystal structure and synthesis

The crystal structure of the compound adopts a face-centered cubic arrangement related to structures characterized by X-ray diffraction groups at Brookhaven National Laboratory, Argonne National Laboratory, Oak Ridge National Laboratory, Rutherford Appleton Laboratory, and Diamond Light Source; potassium occupies interstitial sites analogous to intercalation motifs documented by teams at University of Geneva, University of Illinois Urbana-Champaign, and University of Pennsylvania. Synthetic routes were developed by collaborative efforts spanning Mitsubishi Chemical, Exxon Research, Toho Chemical, University of Oxford, and University of Amsterdam, employing vapor-deposition, solid-state reaction, and electrochemical intercalation techniques similar to work at Politecnico di Milano, University of Tokyo, and Seoul National University. Structural refinements relied on methods pioneered at Lawrence Berkeley National Laboratory, Paul Scherrer Institute, Institut Laue-Langevin, National Institute of Standards and Technology, and SPring-8.

Electronic properties and superconductivity

K3C60 exhibits metallic conductivity and superconductivity with critical temperatures influenced by lattice spacing, a subject explored by experimentalists at Max Planck Institute for Solid State Research, University of Cambridge, Columbia University, Yale University, and University of California, San Diego. The superconducting state prompted comparisons to mechanisms debated by theorists from Bardeen, Cooper, Schrieffer-related schools at University of Chicago, University of Illinois, and Caltech, and to unconventional superconductors investigated at Los Alamos National Laboratory and Brookhaven National Laboratory. Pressure-dependent studies linking structural and electronic transitions were pursued at European Synchrotron Radiation Facility, National High Magnetic Field Laboratory, High Field Magnet Laboratory, and Institute for Solid State Physics (University of Tokyo).

Magnetism and phase diagram

The magnetic behavior and phase diagram of K3C60—showing correlations, possible antiferromagnetism, and proximity to Mott-insulating states—were mapped by groups at University of British Columbia, University of Maryland, University of Geneva, Weizmann Institute of Science, and University of Stuttgart. Phase boundaries and doping effects were compared with studies of correlated materials at ISIS Neutron and Muon Source, NIST Center for Neutron Research, Institute Laue-Langevin, Los Alamos National Laboratory, and Paul Scherrer Institute. Magnetic resonance and susceptibility measurements mirrored approaches used by teams at ETH Zurich, University of Oxford, Harvard-Smithsonian Center for Astrophysics, University of Michigan, and University of Tokyo.

Spectroscopic and transport studies

Spectroscopic probes including photoemission spectroscopy and Raman spectroscopy were applied by collaborations including Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Bell Labs, Lawrence Berkeley National Laboratory, and DESY; transport measurements were performed by experimentalists at MIT, Columbia University, University of California, Santa Barbara, Imperial College London, and Seoul National University. Optical conductivity, tunneling, and infrared studies leveraged setups and expertise from Max Planck Institute for Solid State Research, University of Cambridge, Brookhaven National Laboratory, Argonne National Laboratory, and Cornell University. Results were interpreted in the context of methods developed at Rice University, Princeton University, École Polytechnique, University of Tokyo, and University of Oxford.

Theoretical models and mechanisms

Theoretical descriptions combined electron-phonon coupling, Jahn–Teller effects, and electron-electron correlations in frameworks advanced by researchers associated with Bardeen, Cooper, Schrieffer legacy groups, as well as by theorists at Institute for Advanced Study, Princeton University, Ecole Normale Supérieure, University of California, Berkeley, and Harvard University. Dynamical mean-field theory and Hubbard-model–based approaches were developed at École Polytechnique Fédérale de Lausanne, Rutgers University, University of Cambridge, Max Planck Institute for the Physics of Complex Systems, and University of Geneva. Competing mechanisms echo debates present in work from Bell Labs, Los Alamos National Laboratory, Brookhaven National Laboratory, Columbia University, and Stanford University.

Applications and materials engineering

While primarily of fundamental interest, K3C60 stimulated applied-research efforts at industrial and academic centers such as Eastman Kodak Company, Sony Corporation, Roche, LG Electronics, Siemens, Samsung Electronics, IBM Research, and Hitachi for potential electronic, superconducting, and molecular-assembly applications. Materials-engineering strategies for stability, thin-film growth, and device integration were pursued at MIT, Stanford University, University of Cambridge, Tokyo Institute of Technology, and National Institute for Materials Science (Japan), drawing on fabrication methods developed at Cornell University, University of Illinois Chicago, University of California, Santa Barbara, Korea Advanced Institute of Science and Technology, and Tata Institute of Fundamental Research.

Category:Fullerenes