Researchers at Brown University have found a way to make bismuth ferrite thin enough for computer chips without losing the electrical and magnetic properties that could let future electronics, including AI hardware, run on dramatically less energy.
The team grew bismuth ferrite, a widely studied multiferroic, as part of a three-layer system that eliminates the "dead layer" effect, in which very thin multiferroics lose the behavior that makes them valuable. The findings were published in the journal Nature Materials.
Multiferroics combine electrical and magnetic properties that can be controlled together using extremely small voltages. Applying a small voltage can reverse the material's electrical polarization, offering a way to store digital information as binary values using very little electricity. Because the magnetic behavior is linked to the polarization, that information can also be read magnetically, which could enable memory and logic components that use far less energy than existing technology.
The obstacle has been size. Modern chips require exceptionally thin layers, but multiferroics typically stop functioning properly at such dimensions for two reasons: their atomic structure becomes distorted, and internal electric fields interfere with the polarization. Together these effects destroy the material's ferroelectric and magnetic behavior.
The Brown team addressed both causes. They deposited the bismuth ferrite onto a foundation of dysprosium scandate, a compound derived from rare earth elements whose crystal structure has slightly smaller dimensions, placing the film under compression that helps preserve its atomic arrangement. A second metallic layer was added to counteract the unwanted electric fields, protecting the polarization. The result keeps the film's multiferroic properties intact even at just a few angstroms thick.
"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. "We show that you can make this material basically as thin as you want, down to a few angstroms, and it's still ferroelectric, and it's still magnetic."
The engineering did more than preserve the material's original capabilities. The layered structure caused the bismuth ferrite to exhibit altermagnetism, an uncommon form of magnetism that combines traits of ferromagnets and antiferromagnets. Ferromagnets produce strong, easy-to-read magnetic signals but are relatively slow and generate stray fields that make dense packing difficult; antiferromagnets can operate much faster and avoid those stray fields, but their signals are much harder to detect. “Altermagnets are kind of the best of both worlds, they can be fast, densely integrated and still provide a strong electrical signal for readout,” Caretta said.
Caretta said the findings could bring multiferroics closer to practical use in low-power memory and computing devices as AI drives up demand for computing power and developing hardware that consumes less electricity becomes an increasingly important goal, though the technology still needs further development before it can reach commercial chips. “We know the underlying properties are already there in the bulk materials,” he said. “The trick is learning how to engineer them into a form that's useful, and sometimes even better than what nature gives us.”
The research received funding from the U.S. Army Research Office, the National Science Foundation and the U.S. Department of Energy.
Analysis
Why This Matters
- Artificial intelligence's growing appetite for computing power makes hardware that consumes less electricity an urgent goal, and multiferroics could deliver memory and logic that run on very small voltages.
- The work removes a long-standing materials barrier, showing that the dead layer effect can be overcome rather than merely mitigated.
- The unexpected emergence of altermagnetism could combine speed, dense integration and strong readout signals in one material.
Background
Multiferroics are a class of materials whose electrical and magnetic properties are coupled, meaning both can be controlled together via small voltages. Their practical use in conventional chips has been blocked by the dead layer effect, where ultra-thin films lose the very properties that make them valuable. This research demonstrates a fabrication method that preserves those properties at a few atoms thick and, in doing so, produces a magnetic state not present in the original material.
What to Watch
- Whether the technique translates from bismuth ferrite to other multiferroic compounds.
- Whether the thin films can be integrated into working memory or logic devices in follow-up research.
- How quickly the approach moves from the laboratory toward industrial chip manufacturing processes.
Checked
11 claims in this story checked against 1 source: 9 supported.
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- SupportedBrown’s team has overcome the dead-layer problem that had impeded thin multiferroics for energy-efficient chips.Latest Science News -- ScienceDaily: “Researchers at Brown University have now developed a way to overcome this limitation.”
- Partly supportedThe three-layer technique preserves bismuth ferrite’s properties at a few angstroms and produces a useful new form of magnetism.Latest Science News -- ScienceDaily: “Together, these changes allow the bismuth ferrite film to retain its multiferroic properties even when reduced to just a few angstroms in thickness.”
- SupportedCaretta said, “We've established that we can get rid of the dead layer. We show that you can make this material basically as thin as you want, down to a few angstroms, and it's still ferroelectric, and it's still magnetic.”Latest Science News -- ScienceDaily: “"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. "We show that you can make this material basically as thin as you want -- down to a few angstroms -- and it's still ferroelectric, and it's still magnetic."”
- SupportedCaretta said, “Altermagnets are kind of the best of both worlds, they can be fast, densely integrated and still provide a strong electrical signal for readout.”Latest Science News -- ScienceDaily: “"Altermagnets are kind of the best of both worlds -- they can be fast, densely integrated and still provide a strong electrical signal for readout."”
- SupportedCaretta said, “We know the underlying properties are already there in the bulk materials. The trick is learning how to engineer them into a form that's useful, and sometimes even better than what nature gives us.”Latest Science News -- ScienceDaily: “"We know the underlying properties are already there in the bulk materials," Caretta said. "The trick is learning how to engineer them into a form that's useful -- and sometimes even better than what nature gives us."”
- SupportedThe team deposited bismuth ferrite on dysprosium scandate, which compresses the film, and added a metallic layer to counter unwanted electric fields.Latest Science News -- ScienceDaily: “That mismatch places the bismuth ferrite under compression, helping preserve the atomic structure required for its electrical and magnetic properties to remain intact. The team also incorporated a second metallic layer designed to counteract unwanted electric fields.”
- SupportedThe layered structure caused the bismuth ferrite to exhibit altermagnetism.Latest Science News -- ScienceDaily: “The engineered layers caused the bismuth ferrite to exhibit altermagnetism, an unusual form of magnetism that combines useful characteristics of two more familiar magnetic states: ferromagnetism and antiferromagnetism.”
- SupportedApplying a small voltage can reverse a multiferroic’s polarization, potentially storing binary information with little electricity, which can then be retrieved magnetically.Latest Science News -- ScienceDaily: “Applying a small voltage can reverse this polarization, effectively switching the positions of the positive and negative charges. This provides a potential way to store digital information as binary values (ones and zeros) using very little electricity. Because the material's magnetic behavior is linked to its electrical polarization, the stored information can also be retrieved magnetically.”
- SupportedFerromagnets have strong, readable signals but are relatively slow and have stray fields that hinder dense packing; antiferromagnets can be faster and avoid stray fields but are harder to detect.Latest Science News -- ScienceDaily: “The challenge is that they are relatively slow, and their stray magnetic fields make it difficult to pack devices densely on a chip without interference. Antiferromagnets can operate much faster and avoid those stray fields, but their signals are much harder to detect.”
- Partly supportedCaretta said the findings could bring multiferroics closer to practical low-power memory and computing, while the technology still needs further development before commercial chips.Latest Science News -- ScienceDaily: “Caretta believes the new findings could help bring multiferroic materials closer to practical use in low-power memory and computing devices. Although the technology still needs further development before it can be incorporated into commercial chips, the research demonstrates that a long-standing materials limitation can be overcome.”
- SupportedThe findings were published in Nature Materials.Latest Science News -- ScienceDaily: “The findings were published in the journal Nature Materials .”