Semiclassical dynamics of spin density waves

Abstract

Spin density waves (SDW) provide a canonical example of quantum states with spontaneously broken symmetries. The dynamics of SDWs in Mott insulators is described by the well-known Holstein-Primakoff Hamiltonian, which is equivalent to the semiclassical Landau-Lifshitz equation. Based on a real-space formulation of the time-dependent Hartree-Fock method, the authors demonstrate how to extend the semiclassical dynamics description to the case of itinerant magnets or Mott systems with a moderate charge gap. They further show that, within the adiabatic approximation, the SDW dynamics is governed by a generalized quantum Landau-Lifshitz equation.