Fig. 1
Magnon band structure and instability. The band structure of a kagome topological magnetic insulator (TMI) strip with a drive tuned to the edge modes at momentum π (lattice constant a = 1), calculated from the microscopic model described in the text. Instabilities are marked by coloured disks, with the colour representing the size of the imaginary part, in units of J. Bottom left (grey) inset: A sketch of a few unit cells of the kagome lattice, with lattice vectors δi (|δi| = a = 1) and site vectors ρi drawn in. The system we consider is infinite along the x-direction and comprises W = 45 unit cells along the y-direction. Top right (purple) inset: Zoom of the unstable region. Parameters: Dz/J = 0.2, h/J = 0.01, Ω0/J = 2.578, \(\widehat {\mathbf{e}} = (0,1)\), \({\cal{E}}/J = 0.0004\), γ/J = 0.0001
