117 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
Phase diagram, energy scales and nonlocal correlations in the Anderson lattice model
We study the Anderson lattice model with one f-orbital per lattice site as
the simplest model which describes generic features of heavy fermion materials.
The resistivity and magnetic susceptibility results obtained within dynamical
mean field theory (DMFT) for a nearly half-filled conduction band show the
existence of a single energy scale which is similar to the single ion
Kondo temperature . To determine the importance of inter-site
correlations, we have also solved the model within cellular DMFT (CDMFT) with
two sites in a unit cell. The antiferromagnetic region on the phase diagram is
much narrower than in the single-site solution, having a smaller critical
hybridization and N\'eel temperature . At temperatures above
the nonlocal correlations are small, and the DMFT paramagnetic solution is in
this case practically exact, which justifies the ab initio LDA+DMFT approach in
theoretical studies of heavy fermions. Strong inter-site correlations in the
CDMFT solution for , however, indicate that they have to be properly
treated in order to unravel the physical properties near the quantum critical
point.Comment: 10 page
Self consistent GW determination of the interaction strength: application to the iron arsenide superconductors
We introduce a first principles approach to determine the strength of the
electronic correlations based on the fully self consistent GW approximation.
The approach provides a seamless interface with dynamical mean field theory,
and gives good results for well studied correlated materials such as NiO.
Applied to the recently discovered iron arsenide materials, it accounts for the
noticeable correlation features observed in optics and photoemission while
explaining the absence of visible satellites in X-ray absorption experiments
and other high energy spectroscopies.Comment: 3 figs, 4 page
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