Magnetic fluctuations and itinerant ferromagnetism in two-dimensional systems with Van Hove singularities

P. A. Igoshev, A. A. Katanin, V. Yu Irkhin

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

A criterion for ferromagnetism in two-dimensional systems with the Fermi level near Van Hove singularities (VHSs) is analyzed. In the quasistatic approximation applied to a spin-fermion model, it is shown that the spectrum of spin excitations (paramagnons) is positively defined when the interaction I between the electronic and spin degrees of freedom is sufficiently large (I > I c). The critical interaction I c is much greater than its value determined from the Stoner criterion; hence, the latter criterion is not an adequate criterion for ferromagnetism in the presence of Van Hove singularities in the electronic spectrum. By combining the quasistatic approximation with the method of equations of motion, the electronic self-energy is obtained in the first order in the inverse number of spin components.

Original languageEnglish
Pages (from-to)1043-1056
Number of pages14
JournalJournal of Experimental and Theoretical Physics
Volume105
Issue number5
DOIs
Publication statusPublished - Nov 2007
Externally publishedYes

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