1997/08/01 by Marcus Fleck, Andrzej M. Oleś, Andrzej M. Oles +1 · 4 citations
Materials Science · Mathematics · Physics and Astronomy · #Condensed matter physics #Degenerate energy levels #Density of states #Electron #Fermi level #Ferromagnetism #Geometry #Magnetic and transport properties of perovskites and related materials #Mathematics #Physics #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Quantum mechanics #Singularity #Spin (aerodynamics) #Thermodynamics #Van Hove singularity #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.56.3159
published as PRB 56, 3159 (1997) · 8 pages, 7 figures
openalex publication_date 1997/08/01 · arxiv created 1999/11/23 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the magnetic instabilities of the nondegenerate (s-band) and a degenerate (d-band) Hubbard model in two dimensions using many-body effects due to particle-particle diagrams and Hund's rule local correlations. The density of states and the position of the Van Hove singularity change depending on the value of next-nearest-neighbor hopping t^\ensuremath'. The Stoner parameter is strongly reduced in the s-band case, and ferromagnetism survives only if the electron density is small and the band has flat regions. Due to next-nearest-neighbor hopping there are flat regions in \ensuremathΓ\ensuremath-X and \ensuremathΓ\ensuremath-Y directions. In contrast, for the d-band case the reduction of the Stoner parameter which follows from particle-particle correlations is much smaller and ferromagnetism survives to a large extent. Inclusion of local spin-spin correlations has a limited destabilizing effect on the magnetic states.