Researchers at Brown University have overcome a longstanding obstacle in building computer chips that could dramatically reduce the energy needed for computing and artificial intelligence, according to ScienceDaily.
Multiferroics combine electrical and magnetic properties that can be controlled together using extremely small voltages. Applying a small voltage can reverse this polarization, switching the positions of those charges. Because the material’s magnetic behavior is linked to its electrical polarization, stored information can be retrieved magnetically.
When multiferroic films become extremely thin for modern electronics, internal electric fields and changing atomic structures and chemical environments can disrupt their functionality. This obstacle, known as the “dead layer” effect, can eliminate the ferroelectric and magnetic behavior needed for electronic applications.
Eliminating the Dead Layer
The research team addressed the problem by growing the multiferroic material as part of a three-layer system. First, they grew bismuth ferrite on dysprosium scandate, a rare earth-based crystalline substrate with a smaller lattice spacing than bismuth ferrite.
“We've established that we can get rid of the dead layer,” said Lucas Caretta, an assistant professor of engineering at Brown who led the work.”
said Lucas Caretta, an assistant professor of engineering at Brown who led the work, as reported by ScienceDaily.
The engineered structure gave the material new magnetic characteristics beyond preserving the material’s original properties. The researchers demonstrated that the thin film exhibits altermagnetism, a magnetic state that could overcome limitations of conventional magnetic materials.
Ferromagnets produce strong, easily readable signals for memory and logic, but they are relatively slow, and their stray magnetic fields hinder dense packing on a chip without interference. Antiferromagnets operate much faster and avoid stray fields, but their signals are harder to detect. Altermagnets provide a combination of fast operation, dense integration, and strong signals.
The findings were published in the journal Nature Materials. The research received funding from the U.S. Army Research Office, the National Science Foundation, and the U.S. Department of Energy.
