High-resolution magnetoelectric imaging of perpendicular magnetization under ferroelectric control in Ni films on BaTiO3

The in plane magnetization of thin films can be electrically controlled via changes of strain1-7, exchange bias8-10, carrier density11 and orbital occupation12. However, electrical control of out of plane magnetization remains elusive13,14. Separately, electrical changes and the resulting magnetic changes are rarely imaged together4, and have not both been captured at high resolution. Here we control out-of-plane magnetization by switching on and off stripe domains15-18 in 100 nm-thick Ni films, via strain from ferroelectric BaTiO3 substrates in which we electrically switch domains and thermally drive phase transitions. The ferromagnetic and ferroelectric domains are imaged together using photoemission electron microscopy, with contrast from x-ray magnetic circular dichroism and x-ray linear dichroism, respectively. Regions in which the electrically driven stripe domain erasure was non volatile and repeatable were identified using magnetic force microscopy. Our methodology permits mechanistic insight into magnetoelectrics at the nanoscale, and our findings could be exploited in perpendicular recording media by patterning below the 125 nm stripe width.