Competition between exchange and magnetostatic energies in domain pattern transfer from BaTiO₃(111) to a Ni thin film

We use spin-polarized low-energy electron microscopy to investigate domain pattern transfer in a multiferroic heterostructure consisting of a (111)-oriented BaTiO3 substrate and an epitaxial Ni film. After in situ thick-film deposition and annealing through the ferroelectric phase transition, interfacial strain transfer from ferroelastic domains in the substrate and inverse magnetostriction in the magnetic thick film introduce a uniaxial in-plane magnetic anisotropy that rotates by 60∘ between alternating stripe regions. We show that two types of magnetic domain wall can be initialized in principle. Combining experimental results with micromagnetic simulations, we show that a competition between the exchange and magnetostatic energies in these domain walls has a strong influence on the magnetic domain configuration.