Dependence of the domain structure transformation kinetics on a temperature in heterophase Co/Pt/Co Films

Abstract

Using Kerr microscopy, the effect of temperature on the displacement of domain walls in ultrathin exchange-coupled ferromagnetic layers in Pt/Co/Pt/Co/Pt heterostructures with perpendicular magnetic anisotropy and a nonmagnetic wedge-shaped spacer is experimentally studied. The exchange interaction between Co layers was studied for spacer thicknesses from 5 to 6 nm in the temperature range from 200 to 300 K. Independent displacement of domain walls in Co layers under a perpendicular magnetic field occurs in the thickness range d0 d dCR. In the temperature range, when the domain walls are moved along the Pt wedge, they are stabilized in the equilibrium positions. These positions depend on the field strength, the thickness of the nonmagnetic interlayer, and temperature and is determined by the balance of forces caused by the external field acting on the boundary, the effective field of the exchange coupling between the layers Co and the coercivity field. After the external field is removed, under the influence of the exchange field, the domain walls relax to the initial state with d = d0. The characteristics of the relaxation process depend on temperature. The mechanism of domain wall stabilization near dCR is considered. It is shown that the critical thickness of the nonmagnetic spacer dCR and the coercivity field have opposite temperature dependences.