Light triggers novel ferroelectric switching mechanism

Researchers at Flinders University have discovered an unexpected way that light can control tiny electronic structures inside advanced materials, a development that could help pave the way for more energy efficient memory devices, sensors and future computing technologies.

The new study seeks inroads into electronic properties and optical science by exploring new energy and material capabilities.

“We discovered that light can control nanoscale ‘bubble’ domains (about the size of just a few billionths of a metre across) inside a special ferroelectric crystal,” said Dr Pankaj Sharma, Senior Lecturer in Experimental Condensed Matter Physics at Flinders University.

“However, while most materials respond while the light is shining on them, what surprised us was that the biggest change happened after the light was switched off. By engineering these nanoscale structures, we may be able to develop faster and more efficient electronic and optoelectronic technologies,” Sharma said.

The study was led by Dr Haoze Zhang, a Postdoctoral Fellow in the Sharma research group at Flinders University’s College of Science and Engineering.

While the nano-domains only responded in a minor way when illuminated with near-visible light, they rapidly expanded the moment the light was switched off. This temporarily switched the electronic state of the crystal’s surface the nano-domains gradually returned to their original configuration.

“This behaviour is unlike anything we have seen before. It reveals a completely new way that light and electronic structures interact inside ferroelectric materials,” Zhang said.

Using advanced microscopy and electrical measurements, the Flinders researchers with collaborators from UNSW Sydney, India and the US tracked how electrical charges move through the material during and after illumination.

They found that electrons accumulate near the surface while the light is on and are suddenly released when the light is removed, triggering the rapid switching process.

Ferroelectric materials are emerging for promising new applications in next-generation computing, non-volatile memory, artificial intelligence hardware, sensors and photonic devices.

“Because the switching occurs after the light is removed, the approach could reduce energy consumption and minimise unwanted heating compared with conventional light-controlled devices,” Zhang said.

The research findings have been published in Advanced Functional Materials.

Image credit: iStock.com/gorodenkoff