Influence of spin-wave excitations on the ferromagnetic phase diagram in the Hubbard model

Article

关键词: ITINERANT FERROMAGNETS;    SELF-CONSISTENT;    LATTICES;    SPECTRA;   

DOI  :  10.1103/PhysRevB.66.195109

来源: SCIE

【 摘 要 】

The subject of the present paper is the theoretical description of collective electronic excitations, i.e., spin waves, in the Hubbard model. Starting with the widely used random-phase approximation, which combines Hartree-Fock theory with the summation of the two-particle ladder, we extend the theory to a more sophisticated single particle approximation, namely, the spectral-density ansatz. Doing so we have to introduce a screened Coulomb interaction rather than the bare Hubbard interaction in order to obtain physically reasonable spinwave dispersions. The discussion following the technical procedure shows that comparison of standard RPA with our new approximation reduces the occurrence of a ferromagnetic phase further with respect to the phase diagrams delivered by the single particle theories.

【 授权许可】

Free