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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Flat-band ferromagnetism and spin waves in topological Hubbard models

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Autor(es):
Doretto, R. L. [1] ; Goerbig, M. O. [2]
Número total de Autores: 2
Afiliação do(s) autor(es):
[1] Univ Estadual Campinas, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP - Brazil
[2] Univ Paris Saclay, Univ Paris Sud, CNRS UMR 8502, Lab Phys Solides, F-91405 Orsay - France
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: Physical Review B; v. 92, n. 24 DEC 18 2015.
Citações Web of Science: 8
Resumo

We study the flat-band ferromagnetic phase of a topological Hubbard model within a bosonization formalism and, in particular, determine the spin-wave excitation spectrum. We consider a square lattice Hubbard model at 1/4-filling whose free-electron term is the p-flux model with topologically nontrivial and nearly flat energy bands. The electron spin is introduced such that the model either explicitly breaks time-reversal symmetry (correlated flat-band Chern insulator) or is invariant under time-reversal symmetry (correlated flat-band Z(2) topological insulator). We generalize for flat-band Chern and topological insulators the bosonization formalism {[}R. L. Doretto, A. O. Caldeira, and S. M. Girvin, Phys. Rev. B 71, 045339 (2005)] previously developed for the two-dimensional electron gas in a uniform and perpendicular magnetic field at filling factor nu = 1. We show that, within the bosonization scheme, the topological Hubbard model is mapped to an effective interacting boson model. We consider the boson model at the harmonic approximation and show that, for the correlated Chern insulator, the spin-wave excitation spectrum is gapless while, for the correlated topological insulator, gapped. We briefly comment on the possible effects of the boson-boson (spin-wave-spin-wave) coupling. (AU)

Processo FAPESP: 10/00479-6 - Sistemas magnéticos bidimensionais
Beneficiário:Ricardo Luis Doretto
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores