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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Flat-band ferromagnetism and spin waves in topological Hubbard models

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Doretto, R. L. [1] ; Goerbig, M. O. [2]
Total Authors: 2
[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
Total Affiliations: 2
Document type: Journal article
Source: Physical Review B; v. 92, n. 24 DEC 18 2015.
Web of Science Citations: 8

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)

FAPESP's process: 10/00479-6 - Two-dimensional magnetic systems
Grantee:Ricardo Luis Doretto
Support type: Research Grants - Young Investigators Grants