Publicação
Topological magnons in CrI3 monolayers: an itinerant fermion description
| Resumo: | Magnons dominate the magnetic response of ferromagnetic two-dimensional crystals such as CrI3. Because of the arrangement of Cr spins in a honeycomb lattice, magnons in CrI3 bear a strong resemblance with electrons in graphene. Neutron scattering experiments carried out in bulk CrI3 show the existence of a gap at the Dirac points, conjectured to have a topological nature. We propose a theory for magnons in CrI3 monolayers based on an itinerant fermion picture, with a Hamiltonian derived from first principles. We obtain the magnon dispersion for 2D CrI3 with a gap at the Dirac points with the same Berry curvature in both valleys. For CrI3 ribbons, we find chiral in-gap edge states. Analysis of the magnon wave functions in momentum space confirms their topological nature. Importantly, our approach does not require a spin Hamiltonian, and can be applied to insulating and conducting 2D materials with any type of magnetic order. |
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| Autores principais: | Costa, A. T. |
| Outros Autores: | Santos, D. L. R.; Peres, N. M. R.; Fernández-Rossier, J. |
| Assunto: | 2D magnets Fermionic Hamiltonian Magnons Topological matter Trihalides Van der Waals magnets |
| Ano: | 2020 |
| País: | Portugal |
| Tipo de documento: | artigo |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Magnons dominate the magnetic response of ferromagnetic two-dimensional crystals such as CrI3. Because of the arrangement of Cr spins in a honeycomb lattice, magnons in CrI3 bear a strong resemblance with electrons in graphene. Neutron scattering experiments carried out in bulk CrI3 show the existence of a gap at the Dirac points, conjectured to have a topological nature. We propose a theory for magnons in CrI3 monolayers based on an itinerant fermion picture, with a Hamiltonian derived from first principles. We obtain the magnon dispersion for 2D CrI3 with a gap at the Dirac points with the same Berry curvature in both valleys. For CrI3 ribbons, we find chiral in-gap edge states. Analysis of the magnon wave functions in momentum space confirms their topological nature. Importantly, our approach does not require a spin Hamiltonian, and can be applied to insulating and conducting 2D materials with any type of magnetic order. |
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