FisMat2017 - Submission - View

Abstract's title: Cooling quasiparticles in A3C60 fullerides by excitonic mid-infrared absorption
Submitting author: Andrea Nava
Affiliation: SISSA - Trieste
Affiliation Address: Scuola Internazionale Superiore di Studi Avanzati - via Bonomea, 265 - 34136 Trieste ITALY
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: Claudio Giannetti (ILAMP - Università Cattolica del Sacro Cuore, Brescia I-25121, Italy), Antoine Georges (Centre de Physique Théorique, Ecole Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France and Collége de France, 11 place Marcelin Berthelot, 75005 Paris, France and Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland), Erio Tosatti (SISSA, Via Bonomea 265, I-34136 Trieste, Italy and CNR-IOM Democritos, Via Bonomea 265, I-34136 Trieste, Italy and ICTP, Strada Costiera 11, I-34151 Trieste, Italy), and Michele Fabrizio (SISSA, Via Bonomea 265, I-34136 Trieste, Italy)
Abstract

Superconducting alkali doped fullerenes A3C60 are molecular compounds where several actors play together to determine an intriguing physical behaviour. The freshest inroad in the ever-surprising physics of fullerides is the behaviour under intense infrared (IR) excitation. Signatures attributable to a transient superconducting state extending up to temperatures ten times higher than the equilibrium Tc=20K have been discovered in K3C60 after ultra-short pulsed IR irradiation – an effect which still appears as remarkable as mysterious. Motivated by the observation that the phenomenon is observed in a broad pumping frequency range that coincides with the mid-infrared electronic absorption peak still of unclear origin, we argue that this broad absorption peak represents a ”super-exciton” involving the promotion of one electron from the t1u half-filled state to a higher energy empty t1g state, dramatically lowered in energy by the large dipole-dipole interaction acting in conjunction with Jahn Teller effect within the enormously degenerate manifold of (t1u)2(t1g)1 states. Both long-lived and entropy-rich because they are triplets, the IR-induced excitons act as a sort of cooling mechanism that permits transient superconductive signals to persist up to much larger temperatures.