insulator regime. We calculate the parameters of the corresponding tight-binding model
using Peierls substitution and “localized Wannier states method” and derive the low-energy
spin Hamiltonian for bosons and fermions. The spin Hamiltonian is a combination of
Heisenberg model, quantum compass model<? format?> and Dzyaloshinskii-Moriya
interactions and it has a rich classical phase diagram with collinear, spiral and vortex …