Uniaxial strain modulation of the skyrmion phase transition in ferromagnetic thin films

Abstract

Mechanical control of magnetic order through strain is an important and promising approach in the development of advanced spintronics devices. Here, using a real-space phase-field model based on Ginzburg-Landau theory, we explore the uniaxial strain modulation of topological phase transition in ferromagnetic thin films. In the phase-field model, a magnetoelastic coupling between magnetization and strain, rather than the strain-induced anisotropic Dzyaloshinskii-Moriya interaction, is introduced to describe the strain-modulated anisotropic deformation and topological phase transition of skyrmions. The phase-field simulations show that a uniaxial tensile strain in the ferromagnetic thin films can not only change the wavelength and propagation direction of the spin spiral in helical phase but also induce topological phase transitions of skyrmions. Under specific magnetic fields, the ferromagnetic thin film exhibits the ferromagnetic-to-skyrmion and skyrmion-to-helical phase transitions serially when the uniaxial tensile strain increases, which are different from those induced by uniaxial stress in bulk ferromagnets. The present work not only provides a magnetoelastic coupling mechanism on the uniaxial strain control of topological magnetic structures but also suggests an effective way to tune the electromagnetic properties of ferromagnetic thin films for a new generation of spintronic devices based on skyrmions.