Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2001-08-17
Physics
Condensed Matter
Strongly Correlated Electrons
14 pages, 4 figures
Scientific paper
10.1103/PhysRevB.65.174424
A theory of Kondo lattices or a $1/d$ expansion theory, with $d$ spatial dimensionality, is applied to studying itinerant-electron ferromagnetism. Two relevant multi-band models are examined: a band-edge model where the chemical potential is at one of band-edges, the top or bottom of bands, and a flat-band model where one of bands is almost flat or dispersionless and the chemical potential is at the flat band. In both the models, a novel ferromagnetic exchange interaction arises from the virtual exchange of pair excitations of quasiparticles; it has two novel properties such as its strength is in proportion to the effective Fermi energy of quasiparticles and its temperature dependence is responsible for the Curie-Weiss law. When the Hund coupling $J$ is strong enough, the superexchange interaction, which arises from the virtual exchange of pair excitations of electrons across the Mott-Hubbard gap, is ferromagnetic. In particular, it is definitely ferromagnetic for any nonzero $J>0$ in the large limit of band multiplicity. Ferromagnetic instability occurs, when the sum of the two exchange interactions is ferromagnetic and it overcomes the quenching of magnetic moments by the Kondo effect or local quantum spin fluctuations and the suppression of magnetic instability by the mode-mode coupling among intersite spin fluctuations.
No associations
LandOfFree
Theory of itinerant-electron ferromagnetism does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Theory of itinerant-electron ferromagnetism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Theory of itinerant-electron ferromagnetism will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-544064