An international team led by researchers from the NIST Center for Nanoscale Science and Technology have discovered a new way to simultaneously image both the ferromagnetic and the ferroelectric domain structures of multilayer devices in which a ferromagnetic film is grown on a ferroelectric substrate. These structures have attracted significant recent interest due to their ability to efficiently use voltage to change the magnetization in low-energy magnetic devices.
The researchers' technique uses a scanning electron microscope (SEM) to provide a quantitative picture of how the ferromagnetic and ferroelectric structures interact. The technique simultaneously measures the SEM's low energy secondary electrons and high energy elastically backscattered electrons. The low energy electrons probe a sample's outermost few nanometers, with their spin polarization measuring the magnetization direction in the ferromagnetic surface film. The backscattered electrons probe deeper into the material's bulk. They detect the sample's crystal structure and reveal its underlying ferroelectric structure. By simultaneously measuring the structures, the technique avoids the systematic errors common to methods requiring multiple measurements taken under different conditions and at different times.