Helimagnetic thin films: surface reconstruction, surface spin-waves and magnetization

Quantum properties of a helimagnetic thin film of simple cubic lattice with Heisenberg spin model are studied using the Green's function method. We find that the spin configuration across the film is strongly non uniform. Using the exactly determined spin configuration we calculate the spin-wave spectrum and the layer magnetizations as functions of temperature T. We show the existence of surface-localized modes which strongly affect the surface magnetization. We also show that quantum fluctuations cause interesting spin contractions at T = 0 and give rise to a cross-over between layer magnetizations at low T .