Orbital-selective nature of the 3d electronic structure of the ThFeAsN superconductor

Abstract

Based on local-density approximation plus dynamical mean-field theory (LDA + DMFT) calculations, we perform a comprehensive analysis of electronic structure reconstruction of the ThFeAsN superconductor, showing how the normal and s wave superconducting spectra are reshaped by many-particle electron-electron interactions. Here, the ThFeAsN parent compound is described as an orbital-selective marginal Fermi liquid metal, with coexisting Fermi liquid quasiparticles and pseudogapped electronic states. Upon electron doping, an additional Kondo insulating state is predicted to exist in this system. Furthermore, we show how dynamical correlations strongly renormalize the bare Bogoliubov quasiparticles in the s wave superconducting state into totally correlated lineshapes. These findings contribute to the microscopic understanding of the role played by dynamical multiorbital electronic correlations in the low energy spectrum relevant to unconventional Fe-based superconductors.

Normal-state correlated electronic structure of the tetragonal TlNi2Se2 superconductor

“…Similar selfenergy behavior to that shown in Fig. 6, with sublinear energy dependence, was also found in tetragonal Fe systems [20,42], suggesting hidden marginal Fermi-liquidness at the border of the strain-induced Mott transition in TlNi 2 Se 2 . Finally, since in DMFT the self-energy is momentum independent, the quasiparticle residue Z a of an orbital a, which defines the renormalized Fermi energy, directly yields the effective electron mass enhancement:…”

“…While in the orbital-selective metal regime Im a (ω) shows quadratic frequency dependence, in the Mott-Dirac [42] phase at U c , Im a (ω) nearly vanishes at low energies instead of having a pole at E F , as would occur in a conventional Mott insulator. As pointed out in earlier studies of tetragonal Fe-based materials [20,42], this aspect is somehow reminiscent of marginal, Mott-Dirac liquids where the massive Dirac-like fermions display deviations from the −ω 2 FL form at small ω, which in turn is consistent with (sub)linear ω dependence of marginal FLs [43]. Similar selfenergy behavior to that shown in Fig.…”

“…6 we show the U dependence of the self-energy imaginary (main panels) and real (insets) parts associated with the active Ni-3d orbitals of TlNi 2 Se 2 . Comparing our results with results for the ThFeAsN superconductor [20], for example, we notice similar features despite there being different Coulomb correlation parameters and total electron band fillings n in the two systems, i.e., a clearly visible particle-hole asymmetry in a (ω), which is intensified with increasing U . This particlehole asymmetry is also manifested in the self-energy real parts.…”

“…In this paper, we investigate the role of dynamical MO electronic correlations in the electronic structure reconstruction in the Ni-3d shell of both self-hole-doped (Ni 2+ , see our discussion below) and mixed-valence (Ni 1.5+ ) TlNi 2 Se 2 . As shown in our earlier studies on MO Fe-based superconductors [18][19][20], all five 3d bands need to be considered in order to satisfactorily resolve the correlated electronic state composed of heavy particles in stoichiometric (d 8.5 ) TlNi 2 Se 2 . In MO systems near selective Mott localization, changes in many-particle interactions and electron band filling can lead to interesting physical effects driven by electronic correlations.…”