Pourovskii L V, Hansmann P, Ferrero M, Georges A
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.
Centre de Physique Théorique, CNRS, École Polytechnique, 91128 Palaiseau, France.
Phys Rev Lett. 2014 Mar 14;112(10):106407. doi: 10.1103/PhysRevLett.112.106407. Epub 2014 Mar 13.
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.
