Non-Uniform Strain-Driven Magnetic Domain Wall Motion in PMN-PT/Ni Microstructures

Strain-mediated multiferroic hetero-structures are of great interest since they offer a possible path towards high energy-efficient magnetic memory and logic devices. In this simulation work, a finite difference model is developed to study the strain induced magnetic domain wall (DW) motion in micron size Ni squares onto a PMN-PT substrate. The analysis consists of solving the coupled micromagnetic with elastodynamics. In the model, a non-uniform strain is introduced inside the Ni squares in order to reproduce real devices’ conditions. Initially a magnetic Landau flux-closure state is formed in Ni structures. As an electric field is applied generating compressive strain along the diagonal of the Ni square, a two-domain state forms consisting of two anti-parallel magnetic domains, separated by a DW. A further increase of the electric field produces a lateral motion of the DW. Such DW motion is understood as a result of the minimization of its energy. Good agreement with experimental result is produced by the model. This model helps to better understand the strain-induced magnetic reorientation and DW motion in real multiferroic systems.