title: The strength of electron electron correlation in Cs3C60.
abstract: Cs3C60 is an antiferromagnetic insulator that under pressure (P) becomes metallic and superconducting below Tc = 38 K. The superconducting dome present in the T - P phase diagram close to a magnetic state reminds what found in superconducting cuprates and pnictides, strongly suggesting that superconductivity is not of the conventional Bardeen-Cooper-Schrieffer (BCS) type We investigate the insulator to metal transition induced by pressure in Cs3C60 by means of infrared spectroscopy supplemented by Dynamical Mean-Field Theory calculations. The insulating compound is driven towards a metallic-like behaviour, while strong correlations survive in the investigated pressure range. The metallization process is accompanied by an enhancement of the Jahn-Teller effect. This shows that electronic correlations are crucial in determining the insulating behaviour at ambient pressure and the bad metallic nature for increasing pressure. On the other hand, the relevance of the Jahn-Teller coupling in the metallic state confirms that phonon coupling survives in the presence of strong correlations.
authors.affiliation: Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, V.le Regina Elena 291, Rome, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Baldassarre
authors.affiliation: INSTM Udr Trieste-ST and Elettra - Sincrotrone Trieste S.C.p.A. in Area Science park, S.S. 14, km 163,5, Basovizza, Trieste, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Perucchi
authors.affiliation: Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.|Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Mitrano
authors.affiliation: Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.|Center for Free-Electron Laser Science (CFEL), 22761 Hamburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Nicoletti
authors.affiliation: CELLS-ALBA, Carretera B.P. 1413, Cerdanyola del Valles, 08290, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Marini
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Universitá di Parma, Parma, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Pontiroli
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Universitá di Parma, Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Mazzani
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Universitá di Parma, Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Aramini
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Universitá di Parma, Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Riccó
authors.affiliation: CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Trieste, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Giovannetti
authors.affiliation: CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Trieste, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Capone
authors.affiliation: CNR-IOM, and Dipartimento di Fisica, Universitá di Roma "La Sapienza", Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Lupi