Rice University Researchers Engineer High-Performance Multiferroic

Researchers at Rice University have engineered a new version of a multiferroic material that exhibits significantly higher performance at room temperature than its parent material, a development that could enable the creation of low-energy computing architectures.

The study, published in the Proceedings of the National Academy of Sciences, describes a modified version of bismuth ferrite that demonstrates a 10-fold increase in magnetization and a 100-fold increase in magnetoelectric coupling compared to standard varieties.

To achieve these results, the team mixed bismuth ferrite with barium titanate and grew the material as a thin film on a substrate designed to distort its crystal structure. This process allowed the researchers to simultaneously manipulate both the chemical composition and the mechanical strain of the material.

Nobody had ever dialed both knobs ⎯ the strain and the chemistry ⎯ at once. We were able to combine two different material systems into a new material with a new structure and a new combination of properties.

Lane Martin, Robert A. Welch Professor of Materials Science and NanoEngineering at Rice University

Addressing the Computing Energy Crisis

Modern computing relies on silicon-based systems that store and move information by switching the flow of electrons on or off. While this infrastructure is well-controlled, it has reached an efficiency limit that poses a sustainability risk for the industry.

Lane Martin, who leads the Rice Advanced Materials Institute, noted that electronics today have an energy problem. He stated that within the next five to 10 years, computing could use as much as a quarter to a third of all the power generated.

To solve this, scientists are exploring spintronics, which involves controlling the electron spin—a magnetic property—rather than just the flow of electric charge.

The Role of Multiferroics

Multiferroic materials are a primary focus of this research because they possess multiple order parameters. The most relevant for computing are ferroelectric properties, which allow for spontaneous polarization that can be switched with an electric field, and magnetic properties.

The coupling between these two properties is known as magnetoelectricity. This enables an electric field to change a material’s magnetism or a magnetic field to change its polarization. Such a mechanism could provide the physical basis for memory and logic operations that require far less energy than current systems, potentially combining both functions into a single element.

According to Martin, multiferroics have been studied in earnest for 20-25 years, but the primary challenge has been finding a single material that maintains strong ferroelectric and magnetic properties at room temperature.

Unexpected Material Behavior

The Rice University team, including first author and postdoctoral researcher Tae Yeon Kim, found that incorporating barium titanate—a nonmagnetic perovskite—actually increased the overall magnetization of the system. This was an unexpected result, as bismuth ferrite’s antiferromagnetic order typically cancels out net magnetization.

By altering the lattice parameters and electronic interactions through the combination of chemistry and strain, the researchers modified the magnetic alignment in ways that improved functional performance.

What we have is the fun part of science. When a material does something unexpected, we have to then figure out why.

Lane Martin, Robert A. Welch Professor of Materials Science and NanoEngineering at Rice University

The research establishes a broader strategy for designing new multiferroics by combining structural and chemical modifications. This approach may guide the development of next-generation electronic and spintronic devices that operate with significantly improved energy efficiency.