On the origin of the quasi-particle peak in Cr(001) surfaces

Abstract

In the spectral density of Cr(001) surfaces a sharp resonance close to the Fermi level is observed in both experiment and theory. For the physical origin of this peak two mechanisms were proposed. A single particle dz2 surface state renormalised by electron-phonon coupling and an orbital Kondo effect due to the degenerate dxz/dyz states. Despite several experimental and theoretical investigations, the origin is still under debate. In this work we address this problem by two different approaches of the dynamical mean-field theory. First, by the spin-polarized T-matrix fluctuation exchange approximation suitable for weakly and moderately correlated systems. Second, by the non-crossing approximation derived in the limit of weak hybridization (i.e. for strongly correlated systems) capturing Kondo-like processes. By using recent continuous-time quantum Monte Carlo calculations as a benchmark, we find that the high-energy features, everything except the resonance, of the spectrum is captured within the spin-polarized T-matrix fluctuation exchange approximation. More precisely the particle-particle processes provide the main contribution. For the non-crossing approximation it appears that spin-polarized calculations suffer from spurious behavior at the Fermi level. Then, we turned to non spin-polarized calculations to avoid this unphysical behavior. By employing two plausible starting hybridization functions, it is observed that the characteristics of the resonance are crucially dependent on the starting point. It appears that only one of these starting hybridizations could result in an orbital Kondo resonance in the presence of a strong magnetic field like in the Cr(001) surface. It is for a future investigation to first resolve the unphysical behavior within the spin-polarized non-crossing approximation and then check for an orbital Kondo resonance.

References in corpus (15)

• Topological insulators and superconductors
• Electronic Structure Calculations with Dynamical Mean-Field Theory: A Spectral Density Functional Approach
• A continuous-time solver for quantum impurity models
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• The Hubbard Model at Infinite Dimensions: Thermodynamic and Transport Properties
• Theory of quasiparticle spectra for Fe, Co, and Ni: bulk and surface
• Anderson impurity model at finite Coulomb interaction U: generalized Non-crossing Approximation
• Spectral Properties of the Anderson Impurity Model, Comparison of Numerical Renormalization Group and Non--Crossing Approximation
• Electronic structure and magnetic properties of correlated metals: A local self-consistent perturbation scheme
• Correlation effects in total energy of transition metals and related properties
• Relevance of complete Coulomb interaction matrix for the Kondo problem: Co impurity on Cu(111)
• Strength of the Effective Coulomb Interaction at Metal and Insulator Surfaces
• Conserving Diagrammatic Approximations for Quantum Impurity Models: NCA and CTMA
• Orbital Kondo effect in Cobalt-Benzene sandwich molecules
• Many-body effects on Cr(001) surfaces: An LDA+DMFT study

Cited by in corpus (1)

• An ab-initio study of the electron-phonon coupling within a Cr(001)-surface