Research area | Mathematics, Physics and Engineering |
Title | Topological magnons in CrI(3)monolayers: an itinerant fermion description |
Publication Type | Journal Article |
Publication year | 2020 |
Authors | Costa, AT, Santos, DLR, Peres, NMR, Fernandez-Rossier, J |
Journal | 2D MATERIALS |
Volume | 7 |
Number | 4 |
Type of Article | Article |
Keywords | 2D magnets, fermionic Hamiltonian}, topological matter, trihalides, Van der Waals magnets, {magnons |
Abstract | 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 CrI(3)bear a strong resemblance with electrons in graphene. Neutron scattering experiments carried out in bulk CrI(3)show the existence of a gap at the Dirac points, conjectured to have a topological nature. We propose a theory for magnons in CrI(3)monolayers based on an itinerant fermion picture, with a Hamiltonian derived from first principles. We obtain the magnon dispersion for 2D CrI(3)with a gap at the Dirac points with the same Berry curvature in both valleys. For CrI(3)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. |
DOI | 10.1088/2053-1583/aba88f |