Proximity-Induced Ferroelectricity for Enhanced Performance

Researchers from Pennsylvania State University have demonstrated that a non-ferroelectric material can acquire ferroelectric properties through interfacing with a ferroelectric material, a phenomenon termed proximity-induced ferroelectricity. The findings were published in Nature.

Ferroelectric materials are characterized by their ability to reverse their polarized positive and negative charges under an external electric field, akin to how the poles of a magnet can switch. This property makes them valuable for applications in data storage and wireless communication, as they can maintain their polarized states until further electrical power is applied.

The discovery offers a novel approach to inducing ferroelectricity in materials without altering their chemical composition, which often compromises other desirable properties. Researchers highlight significant implications for quantum computing, optoelectronics, and next-generation processors.

This work shows we can generate ferroelectricity in a material that does not have those properties just by stacking it with a material that is ferroelectric. And, so, it has to be that the two materials are talking to each other. We call it proximity ferroelectricity because it is an effect of being in contact.

Jon-Paul Maria, Professor and Study Lead Author, The Pennsylvania State University

Researchers at the University of Kiel in Germany and Penn State have developed new families of nitride and oxide ferroelectric materials. These materials exhibit similar properties to traditional ferroelectrics but have simpler structures and preparation methods. This enables direct integration with common semiconductors like silicon, thereby enhancing their technological applicability.

The current research builds on these findings by demonstrating how comparable materials can be produced without the chemical modifications previously required for fabrication, according to the researchers.

The community got very excited in the last few years about two new emergent families of ferroelectrics that show very promising future impacts on electronic devices. This is now another step in that process. It is the second time that we have been stunned about what we did not know about ferroelectricity after 100 years of research.

Jon-Paul Maria, Professor and Study Lead Author, The Pennsylvania State University

In previous work, Maria and his team developed magnesium-substituted zinc oxide thin films, a ferroelectric material exhibiting promising performance but accompanied by inherent trade-offs. While zinc oxide itself lacks ferroelectric properties, it retains several advantageous characteristics.

The introduction of magnesium into zinc oxide induces ferroelectricity; however, this modification compromises critical attributes, including thermal conductivity during device operation and long-range optical transmission.

The researchers have now demonstrated that by interfacing pure zinc oxide with a ferroelectric material, such as magnesium-substituted zinc oxide thin films, ferroelectricity can be induced via proximity ferroelectricity.

Imagine that I can stack these layers on top of each other, where one is ferroelectric, and the other is normally not, but through proximity ferroelectricity. It can exhibit the polarization reversal in its pure state. That is the real appeal.

Jon-Paul Maria, Professor and Study Lead Author, The Pennsylvania State University

The ferroelectric layer constitutes only about 3 % of the stack's total volume, allowing the majority of the material to retain its most desirable properties. The researchers noted that the ferroelectric, or switching layer, can be incorporated as an internal layer or positioned on the top or bottom of the stack.

This technique could enable new approaches to engineering ferroelectric properties and discovering novel materials. The researchers observed proximity ferroelectricity in oxide, nitride, and combined nitride-oxide systems, suggesting the presence of a general mechanism.

Maria emphasized that the current work merely scratches the surface of the technique's potential and that future research should explore additional material compositions.

The technology may be particularly helpful in creating electronic applications for next-generation optics. According to Maria, finding ways to reduce energy consumption is a big problem in computing, and one solution is to switch from using electronics to communicate with processors to using light.

Maria said, “And a big part of that may be this next generation of optoelectronic materials. Our findings could be one candidate. Alternatively, this could mean that other enabling materials are already known, and exciting functional properties like ferroelectric switching just need unlocking using this proximity effect.”

The study was funded by the US Department of Energy, the US National Science Foundation, and the US Department of Defense.

Journal Reference:

‌Skidmore, C. H., et al. (2025) Proximity ferroelectricity in wurtzite heterostructures. Nature. doi.org/10.1038/s41586-024-08295-y.