Brown researchers preserve electrical and magnetic behavior in ultrathin chip material

Brown University researchers have kept a promising computing material electrically and magnetically active even when reduced to a few angstroms in thickness. The result addresses a barrier to making smaller, lower-power components. Brown’s November 12 account, published by ScienceDaily, describes a materials finding with potential uses in memory and logic—not a finished AI chip.

Keeping two useful properties together

The material is bismuth ferrite, part of a class called multiferroics. These materials couple electrical and magnetic properties, allowing a small voltage to control behavior that could be useful for computing. Their attraction is not simply being magnetic: it is the connection between an electrical change and a magnetic response.

Inside the material, repeating atomic units have positive and negative charges positioned on opposite sides. This separation is called electrical polarization. A small voltage can reverse it, offering a possible way to represent digital ones and zeros. Because the magnetic behavior is linked to that polarization, information could also be read magnetically.

But shrinking multiferroics to the thin layers needed for chips can destroy those useful properties. Two effects contribute to this “dead layer” problem. The atomic structure becomes distorted, disrupting the arrangement needed for the material to function. Internal electric fields also interfere with polarization until it can no longer be sustained.

A three-layer answer to two failures

The Brown team addressed each failure through the material’s surroundings. Researchers grew bismuth ferrite on a foundation of dysprosium scandate, whose crystal structure has slightly smaller dimensions. That mismatch compresses the bismuth ferrite, helping maintain the atomic arrangement responsible for its electrical and magnetic properties.

An additional metallic layer tackles the other problem by counteracting unwanted electric fields. Together, the layers preserve both the structural conditions and electrical polarization that thinning would otherwise disrupt. The researchers say the resulting films remain ferroelectric—meaning their polarization can be switched—and magnetic at thicknesses of just a few angstroms.

We've established that we can get rid of the dead layer.

Lucas Caretta, Brown engineering assistant professor who led the work

A magnetic bonus, with chips still ahead

The engineered films also exhibited altermagnetic behavior, according to the researchers. This unusual form of magnetism offers a potentially useful combination of characteristics found in two more familiar types: ferromagnetism and antiferromagnetism. The findings appear in Nature Materials under the title “Altermagnetic signatures and topological textures in ultrathin multiferroic BiFeO3.”

Caretta describes the appeal through a tradeoff. Ferromagnets provide strong, easily read magnetic signals, but are relatively slow. Their stray magnetic fields can also interfere with neighboring devices. Antiferromagnets can operate faster and avoid those stray fields, but their signals are harder to detect. Altermagnets, he says, could combine speed and dense integration with a strong electrical signal for readout.

The study also has a public experimental-data record. A September 21 Zenodo deposit contains raw data for the paper’s main and extended figures, alongside software used for analysis and figure generation. That deposit provides access to supporting research materials; it predates the November university account.

For AI hardware, the relevance is a possible route to lower-power memory and logic components, rather than a demonstrated reduction in an AI system’s electricity use. Commercial incorporation still requires further development. The immediate achievement is preserving useful material behavior at extreme thinness while producing magnetic characteristics that may help future device designs.