349 research outputs found
Modelling the Localized to Itinerant Electronic Transition in the Heavy Fermion System CeIrIn5
We address the fundamental question of crossover from localized to itinerant
state of a paradigmatic heavy fermionmaterial CeIrIn5. The temperature
evolution of the one electron spectra and the optical conductivity is predicted
from first principles calculation. The buildup of coherence in the form of a
dispersive many body feature is followed in detail and its effects on the
conduction electrons and optical conductivity of the material is revealed. We
find multiple hybridization gaps and link them to the crystal structure of the
material. Our theoretical approach explains the multiple peak structures
observed in optical experiments and the sensitivity of CeIrIn5 to substitutions
of the transition metal element and may provide a microscopic basis for the
more phenomenological descriptions currently used to interpret experiments in
heavy fermion systems.Comment: 12 pages, 3 figure
Pressure suppression of electron correlation in the collapsed tetragonal phase of CaFe2As2: A DFT-DMFT investigation
Recent studies reveal a pressure induced transition from a paramagnetic tetragonal phase (T) to a collapsed tetragonal phase (CT) in CaFe2As2, which was found to be superconducting with pressure at low temperature. We have investigated the effects of electron correlation and a local fluctuating moment in both tetragonal and collapsed tetragonal phases of the paramagnetic CaFe2As2 using self-consistent DFT-DMFT with continuous time quantum Monte Carlo as the impurity solver. From the computed optical conductivity, we find a gain in the optical kinetic energy due to the loss in Hund's rule coupling energy in the CT phase. We find that the transition from T to CT turns CaFe2As2 from a bad metal into a good metal. Computed mass enhancement and local moments also show a significant decrease in the CT phase, which confirms the suppression of the electron correlation in the CT phase of CaFe2As2
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