Combining ultra-thin molybdenum disulfide with flexible strontium titanate nanomembranes creates advanced materials that can be used in a variety of low-power, high-performance electronic and sensing devices. Credit: Jennifer M McCann/ Penn State. CC BY-NC-ND.

A material’s ‘incipient’ property could help to jumpstart fast, low-power electronics according to new research from the USA.

Scientists at Penn State have harnessed a unique property called incipient ferroelectricity to create a new type of computer memory that could revolutionise how electronic devices work, such as using much less energy and operating in extreme environments like outer space.  

The work focuses on multifunctional two-dimensional field-effect transistors (FETs), which are advanced electronic devices that use ultra-thin layers of materials to control electrical signals, offering multiple functions like switching, sensing or memory in a compact form.

They are ferroelectric-like, meaning the direction of their electric conduction can be reversed when an external electric field is applied to the system.

FETs are essential in computing, since the ferroelectric-like property allows them to shift signals. 

Traditional computing systems, especially artificial intelligence (AI) handling image recognition, consume significant energy.

The ferroelectric transistors’ low power requirements present a sustainable alternative. 

Co-author Harikrishnan Ravichandran, a doctoral student in engineering science and mechanics, said: “AI accelerators are notoriously energy-hungry.

“Our devices switch rapidly and consume far less energy, paving the way for faster, greener computing technologies.”  

Overlooked

Incipient ferroelectricity, a previously overlooked property of FETs, may be to thank for the quicker, more sustainable devices.

Incipient ferroelectricity refers to materials that show signs of temporary, scattered polarisation, meaning parts of it can switch charges like tiny dipoles — opposing magnetic poles a small distance apart — but it does not settle into a stable state under normal conditions. 

Think of it like a material that has the potential to become ferroelectric, but it needs a little push.

Incipient ferroelectricity is means the material is on the verge of becoming ferroelectric — it can hold an electrical charge, but needs certain conditions to achieve an electrical charge.  

Lead author Dipanjan Sen, doctoral candidate in engineering science and mechanics, said: “Incipient ferroelectricity means there’s no stable ferroelectric order at room temperature. Instead, there are small, scattered clusters of polar domains.

“It’s a more flexible structure compared to traditional ferroelectric materials.” 

While this trait is often considered a limitation, the team found that the incipient ferroelectricity became less incipient and more traditional at colder temperatures.

According to Ravichandran, the devices displayed unique behaviours across temperature ranges, suggesting a flexibility that could enable possible new applications.  

Corresponding author Saptarshi Das, Ackley Professor of Engineering and professor of engineering science and mechanics at Penn State, said: “The main goal of the project was to explore whether incipient ferroelectricity, usually seen as a disadvantage because it leads to short memory retention, could actually be useful.

“In cryogenic conditions, this material exhibited traditional ferroelectric-like behaviour suitable for memory applications. But at room temperature, this property behaved differently; it had this relaxor nature.”

Relaxor behaviour

Relaxor behaviour refers to a more disordered, short-range polarisation response.

This type of behaviour is less predictable and more fluid, which contrasts with the stable, long-range order seen in traditional ferroelectrics.

This means the material’s ferroelectric properties are weaker or less stable at room temperature.

Instead of being a drawback, the researchers said it showed potential for use in neuromorphic computing, which aims to imitate how the human brain processes information using neurons and uses much less energy than traditional computers.

Like our brain, it saves energy by only using power when needed, like flipping a light switch on and off, instead of staying on all the time like traditional computers. 

Co-author Mayukh Das, doctoral candidate in engineering science and mechanics said: “These devices acted like neurons, mimicking biological neural behaviour.

“To test this, we performed a classification task using a grid of three-by-three-pixel images fed into three artificial neurons. The devices were able to classify each image into different categories.

“This learning method could eventually be used for image identification and classification or pattern recognition. Importantly, it works at room temperature, reducing energy costs.

“These devices function similarly to the nervous system, acting like neurons and creating a low-cost, efficient computing system that uses a lot less energy.”

Strontium titanate

Collaborators at the University of Minnesota developed the FETs by depositing a layer of atoms on a substrate to form a thin film.

These films, made of strontium titanate, were then combined with molybdenum disulfide, a two-dimensional material.  

Strontium titanate is typically non-ferroelectric, meaning it does not have a permeant electric field.

However, freestanding nanomembranes of strontium titanate exhibit polar order, the researchers said, which can enable the material to exhibit ferroelectric-like behaviour, especially at very low temperatures.  

Strontium titanate thin films, along with their incipient ferroelectricity, are also a perovskite material.

Perovskites, materials with a specific type of crystal structure, are valued for their exceptional electronic properties.  

Sen said: “We were surprised to see that these well-known perovskite materials could exhibit exotic ferroelectric properties at the device level.

“It wasn’t something we anticipated, but once we started fabricating the devices, we saw behaviours that could really redefine advanced electronics.” 

Future research

The researchers noted that future research will include addressing current challenges such as scalability and commercial viability while exploring other potential materials.  

Sen said: “Right now, this is at the research and development stage.

“Perfecting these materials and integrating them into everyday devices like smartphones or laptops will take time, so there’s so much more to explore.

“In addition, we’re examining other materials, like barium titanate, to uncover their potential. The opportunities for growth are immense, both in materials and device applications.” 

The study is published in Nature Communications.