Communications of the ACM
A Step Towards Energy-Efficient Voltage Control of Magnetic Devices
The color SEMPA image shows the direction of the magnetization in the ferromagnet, and the monochrome backscattered electron image shows the domain structure of the underlying ferroelectric.
Credit: NIST News
Researchers at the U.S. National Institute of Standards and Technology and the University of California, Berkeley have developed a method to create simultaneous images of both the magnetic and the electric domain structures in ferromagnetic/ferroelectric multilayer materials.
The researchers say that by combining ferromagnetic and ferroelectric materials, it is possible to create low-power magnetic devices, including memory that can be controlled by electric fields instead of less energy-efficient magnetic fields.
The researchers used scanning electron microscopy with polarization analysis (SEMPA) to directly image the magnetization direction in thin ferromagnetic films made of cobalt-iron that were grown on thicker ferroelectric substrates made of bismuth ferrite. The researchers also imaged the ferroelectric domains using a separate detector to measure higher-energy backscattered electrons from the buried bismuth ferrite.
The SEMPA and backscattered electron images provided new information about the coupling between the two layers that occurs at their interface. The images showed that the local, nanoscale direction of the magnetization of the cobalt-iron film nearly aligns with both the interfacial direction of the ferroelectric polarization and with the induced ferromagnetism of the bismuth ferrite, and by modeling the deviation from perfect alignment, the researchers were able to infer the strength of the interaction at the interface between the two materials.
From NIST News
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