Faster-charging electronics, more efficient power grids and air conditioners that use less electricity may depend on a little-known class of materials now under renewed scrutiny.

Antiferroelectrics — materials that can rapidly switch between polar and antipolar states — have long been studied for high-density energy storage and solid-state cooling. But 75 years after their discovery, researchers say the definition of antiferroelectricity is evolving, a shift that could broaden how these materials are studied and developed.

In a perspective published Feb. 27 in Nature Materials, an international team of experts, including University of Nebraska–Lincoln physicist Alexei Gruverman, reports that the traditional hallmarks of antiferroelectrics no longer capture the full range of materials showing similar behavior.

“The classical definition of antiferroelectricity has been a cornerstone of the field for decades, but it is increasingly clear that it no longer captures the full complexity of emerging modern materials,” said Gruverman, Charles J. Mach Professor of Physics and Astronomy in Nebraska’s College of Arts and Sciences. “By broadening our perspective, we are moving toward a more accurate fundamental picture but also better understanding of the functional behavior that aligns with the recent experimental findings.”

Antiferroelectrics were first predicted in 1951 by famous physicist Charles Kittel and confirmed experimentally the same year by another well-known scientist Gen Shirane. In these materials, neighboring electric dipoles — atomic-scale separations of positive and negative charges — align in opposite directions in their natural state, canceling out overall polarization.

When a strong electric field is applied, the material’s charges flip between opposing arrangements. As the field cycles on and off, this switching produces a distinctive “double hysteresis” loop — two loops stacked together on a graph. This behavior is important because it allows the material to quickly store and release energy, a key property for high-performance capacitors and other electronics. Some antiferroelectrics also change temperature in response to electric fields, opening the possibility of solid-state cooling systems that use less electricity and reduce reliance on conventional refrigerants.

Recent research shows the antipolar alignment of dipoles in antiferroelectrics is more complex than previously thought. Some materials have hybrid or non-collinear arrangements, meaning the tiny dipoles do not follow the simple opposite alignment seen in traditional antiferroelectrics. More surprisingly, some newer materials also show the characteristic double hysteresis loop, even though they do not exhibit the traditional opposite dipole arrangement. The findings suggest that the double hysteresis loop alone is not sufficient to define antiferroelectricity. 

“This modern perspective opens up a new playground for researchers to engineer the so-called pseudo antiferroelectric materials that exhibit the similar switching behavior as classical antiferroelectrics,” Gruverman said. “By moving beyond a narrow structural definition, we can more effectively design the specific functionality needed for the next generation of high-performance energy storage and cooling technologies.”

Released 75 years after antiferroelectrics were first hypothesized and discovered, the international team’s perspective builds on a long history of research while introducing a definition that offers new possibilities for future study and advancement.

“This is one of the best articles I’ve ever been a part of,” Gruverman said. “It reflects more than a year of intensive work, brainstorming and debates across the team, and publishing it in this milestone year feels especially meaningful. I’m confident it will make waves in this field of study.”

Review the perspective in Nature Materials at https://rdcu.be/e50Ou.

Physics