title: Theoretical prediction and spectroscopic fingerprints of an orbital transition in CeCu2Si2.
abstract: We show that the heavy-fermion compound CeCu2Si2 undergoes a transition between two regimes dominated by different crystal-field states. At low pressure P and low temperature T the Ce 4f electron resides in the atomic crystal-field ground state, while at high P or T, the electron occupancy and spectral weight is transferred to an excited crystal-field level that hybridizes more strongly with itinerant states. These findings result from first-principles dynamical-mean-field-theory calculations. We predict experimental signatures of this orbital transition in x-ray spectroscopy. The corresponding fluctuations may be responsible for the second high-pressure superconducting dome observed in this and similar materials.
authors.affiliation: Centre de Physique Théorique, CNRS, École Polytechnique, 91128 Palaiseau, France and Swedish e-science Research Centre (SeRC), Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.
authors.forename: L V
authors.initials: LV
authors.lastname: Pourovskii
authors.affiliation: Centre de Physique Théorique, CNRS, École Polytechnique, 91128 Palaiseau, France.
authors.forename: P
authors.initials: P
authors.lastname: Hansmann
authors.affiliation: Centre de Physique Théorique, CNRS, École Polytechnique, 91128 Palaiseau, France.
authors.forename: M
authors.initials: M
authors.lastname: Ferrero
authors.affiliation: Centre de Physique Théorique, CNRS, École Polytechnique, 91128 Palaiseau, France and Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France and DPMC, Université de Genève, 24 quai Ernest Ansermet, CH-1211 Genève, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Georges