The temperature-strain phase diagrams of ferromagnetic thin films under different magnetic fields

The topological magnetic structures in ferromagnetic thin films, such as magnetic skyrmions, are considered as the potential information carriers for future spintronics memory and logic devices due to their topological stability and controllability. In the application, ferromagnetic thin films often experience different temperatures, strains and magnetic fields. To understand the stability of topological magnetic structures in ferromagnetic thin films under different external conditions is not only of scientific significance but also of practical importance. In this work, a temperature-dependent real space phase field model is proposed to investigate the stable topological magnetic structures in ferromagnetic thin films under different magnetic fields, temperatures and strains. The skyrmions phase, helical phase and ferromagnetic phase are predicted in the ferromagnetic thin films with different magnetic fields, temperatures and strains. The strain is applied in the plane of the films, whereas the magnetic field is applied perpendicular to the plane of the thin films. The temperature-strain phase diagrams of ferromagnetic thin films are constructed under different magnetic fields. It is found that a tensile biaxial strain enhances the stability of skyrmions while skyrmions gradually become unstable when the biaxial strain changes from tensile to compressive. For the uniaxial strain, however, skyrmions can be stabilized under both tensile and compressive strains, which indicates the uniaxial strain is more preferable than biaxial strain for the stability of skyrmions.