Role of rotational symmetry in the magnetism of a multiorbital model

Abstract

Effect of rotationally-invariant Hund's rule coupling on a magnetism of multiorbital Hubbard models is studied within a dynamical mean field theory framework. Comparison of static magnetic susceptibilities and local densities of states of two- and three-orbital models of a complete rotationally invariant Coulomb interaction and a "density-density" Hartree type interaction shows the different role of spin-flip interactions for different band fillings. In the particle-hole symmetric case the Mott-Hubbard physics dominates due to the strong effective Coulomb interaction, while for the multiple electronic configurations away from half-filling (two electrons in the three band model) the formation of local magnetic moments due to Hund's exchange interaction becomes the most significant effect for itinerant magnetic systems. A shift of the temperature of magnetic ordering due to the rotationally-invariant Hund's rule coupling is found to be the largest in a three-orbital model with a two-electron occupancy where the single particle spectrum is metallic and is not sensitive to different forms of the Coulomb vertex. A larger enhancement of the effective mass in a model with a rotationally-invariant interaction is discussed. In the half-filled case we find a drastic change in the density of states close to the Mott transition which is related to the spin-flip Kondo fluctuations in a degenerate orbital case, while the corresponding shift of the magnetic transition temperature is relatively small. It is shown that a change in the ground state degeneracy due to a different symmetry of the Coulomb interaction in the density-density model leads to a breakdown of the quasiparticle peak at the Fermi level in the proximity of a Mott transition on the metallic side. We discuss the relevance of rotationally-invariant Hund's interaction in the transition metal magnetism.

10 pages, 9 figures, 2 tables

References in corpus (13)

• Continuous-time Monte Carlo methods for quantum impurity models
• The numerical renormalization group method for quantum impurity systems
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• Magnetism and Charge Dynamics in Iron Pnictides
• Spin freezing transition and non-Fermi-liquid self-energy in a 3-orbital model
• The coherence-incoherence crossover and the mass-renormalization puzzles in Sr2RuO4
• High-spin to low-spin and orbital polarization transitions in multiorbital Mott systems
• Metal-Insulator phase diagram and orbital selectivity in 3-orbital models with rotationally invariant Hund coupling
• Kondo resonance narrowing in d- and f-electron systems
• Superperturbation solver for quantum impurity models
• Quantum Monte Carlo study for multiorbital systems with preserved spin and orbital rotational symmetries
• Orbital Order, Metal Insulator Transition, and Magnetoresistance-Effect in the two-orbital Hubbard model
• Metal-insulator transition in the two-orbital Hubbard model at fractional band fillings: Self-energy functional approach

Cited by in corpus (3)

• Finite temperature quantum embedding theories for correlated systems
• Magnetism of iron and nickel from rotationally invariant Hirsch-Fye quantum Monte Carlo calculations
• Orbital Rotations induced by Charges of Polarons and Defects in Doped Vanadates