Engineers at Rice University in the U.S. have developed a new room-temperature multiferroic material that shows a 10-fold increase in magnetization and a 100-fold increase in magnetoelectric coupling compared to standard varieties. This new work could pave the way for low-energy computing in the future. 

Modern computing uses silicon, where information is stored by controlling the flow of electrons. While this has worked for us in the past, as the need for data storage increases, the material is also reaching its efficiency limits. 

Computing is accelerating rapidly, leading to skyrocketing energy consumption that could even consume a third of all power generated on the planet. This could make it unsustainable in the long run. This requires a major rethink of how additional electron properties can serve as the basis for new forms of computation.

Multiferroics to the rescue

Multiferroics are materials with multiple order parameters and have been studied for over two decades. The material is promising because of the coupling observed across its magnetic properties. Called magnetoelectricity, this coupling allows an electric field to change a magnetic material’s magnetization, or a magnetic field to change a material’s polarization. 

Since it is much simpler to switch these parameters, the material can be useful for performing memory and logic operations while using far less energy. If required, these two functions can be combined into a single function. 

However, researchers faced a major challenge using a material that was both ferroelectric and magnetic at room temperature. 

Room temperature multiferroic

Bismuth ferrite is a multiferroic material that researchers have previously used. However, it suffers from weak magnetism since its atomic moments cancel each other out. When Rice researchers added a non-magnetic component, barium titanate, to the multiferroic material, they observed an increase in the material’s overall magnetization while preserving its electrical properties. 

The research team, comprising Tae Yeon Kim, a postdoctoral fellow, and Lane Martin, a professor of Materials Science and Engineering at Rice University, was surprised by the large increase in magnetization. 

The synthesis process consists of mixing bismuth ferrite with barium titanate to carefully engineer a strain, then growing the mixture as a thin film on a substrate that distorts its crystal structure. The researchers spent more than six months making and testing samples. This also included asking other team members to independently expand the material to ensure reproducibility. 

“Nobody had ever dialed both knobs ⎯ the strain and the chemistry ⎯ at once,” said Lane Martin, material scientist at Rice University, in a press release. “We were able to combine two different material systems into a new material with a new structure and a new combination of properties.”

While researchers have identified a new material for low-energy computing, they have also advanced multiferroic materials science by combining chemistry and strain to create new structures with unexpected properties. To the researcher’s surprise, adding non-magnetic atoms to the material made it more magnetic. 

The research findings were published in the journal PNAS.