Spectral properties of the two-impurity Anderson model with varying distance and various interactions

Abstract

We present a novel approximation for two interacting magnetic impurities immersed into a noninteracting metallic host. The scheme is based on direct perturbation theory in the hybridization between the impurity and band electrons. This two-impurity enhanced noncrossing approximation (TIE) fully incorporates the indirect interaction between the impurities which are mediated by the conduction electrons as well as additional arbitrary direct interaction matrix elements. We qualify the approximation by investigating the uncoupled case and conclude the TIE to be equally accurate as its single impurity counterpart. The physical properties of the two-impurity Anderson model are first investigated in some limiting cases. In a regime, where each of the uncoupled two impurities would exhibit a pronounced Kondo effect, we ignore the indirect coupling via the conduction band and only incorporate direct interactions. For a ferromagnetic direct exchange coupling, the system displays a behavior similar to a spin-one Kondo effect, while an antiferromagnetic coupling competes with the Kondo effect and produces a pseudogap in the many-body Kondo resonance of the single-particle spectral function. Interestingly, a direct one-particle hopping also produces a pseudogap but additionally pronounced side-peaks emerge. This gap is characteristically different from the case with antiferromagnetic coupling, since it emerges as a consequence of distinct Kondo effects for the bonding and anti-bonding orbital, i.e.\ it reflects a splitting of even and odd parity states.For the general case of only indirect coupling the results show signatures of all the previously discussed limiting cases as function of the impurity-impurity distance. We are led to the conclusion that the well known Doniach-scenario captures essential aspects this model, but the details especially at small distances are more complicated.

References in corpus (11)

• Heavy Fermions and Quantum Phase Transitions
• Nonequilibrium Singlet-Triplet Kondo Effect in Carbon Nanotubes
• Long-range Kondo signature of a single magnetic impurity
• A Tunable Two-impurity Kondo system in an atomic point contact
• Kondo screening cloud in a one dimensional wire: Numerical renormalization group study
• Kondo resonance narrowing in d- and f-electron systems
• Non-Fermi liquid signatures in the Hubbard Model due to van Hove singularities
• Conserving approximations in direct perturbation theory: new semianalytical impurity solvers and their application to general lattice problems
• Coherence scale of coupled Anderson impurities
• Itinerant and local-moment magnetism in strongly correlated electron systems
• The Two-Impurity Anderson Model at Quantum Criticality

Cited by in corpus (12)

• Interplay between Kondo effect and Ruderman-Kittel-Kasuya-Yosida interaction
• Probing Magnetic Excitations and Correlations in Single and Coupled Spin Systems with Scanning Tunneling Spectroscopy
• Exploring the phase diagram of the two-impurity Kondo problem
• Emergent Coherent Lattice Behavior in Kondo Nanosystems
• Dynamical mean-field theory of indirect magnetic exchange
• Effective low-energy description of the two impurity Anderson model: RKKY interaction and quantum criticality
• Strongly correlated multi-impurity models: The crossover from a single-impurity problem to lattice models
• Gutzwiller variational approach to the two-impurity Anderson model at particle-hole symmetry
• Extension of dynamical mean-field theory by inclusion of nonlocal two-site correlations with variable distance
• Non-interacting two-impurity Anderson model on a lattice at particle-hole symmetry
• Quantum oscillations of Kondo screening phases in strong magnetic fields
• Spectral properties of strongly correlated multi impurity models in the Kondo insulator regime: Emergent coherence, metallic surface states and quantum phase transitions