Ferroelectric materials are key components in various information processing devices, including computer memory, transistors, sensors, and actuators. Researchers at Argonne National Laboratory have reported new adaptive behaviors in a ferroelectric material that can evolve in stages depending on the intensity of light pulses it receives. The research involved collaboration with scientists from Rice University, Pennsylvania State University, and DOE's Lawrence Berkeley National Laboratory.
The material studied contains interconnected islands, or domains, that are distinct from one another, similar to oil droplets in water. These domains are only nanometers in size - billionths of a meter - and can rearrange in response to light pulses. This adaptive quality could enable more energy-efficient information processing in future microelectronic applications.
The ferroelectric material used in the experiments is a layered structure of lead and strontium titanate, prepared by collaborators at Rice University. Comprising seven alternating layers, the structure is 1,000 times thinner than a sheet of paper. Earlier, the research team exposed a sample to a single, intense light pulse, which resulted in a uniform nanoscale pattern. In this study, they used multiple weaker light pulses, each lasting a quadrillionth of a second, which led to the formation of various domain structures based on the optical dosage applied.
To capture these nanoscale changes, the team utilized the Nanoprobe (beamline 26-ID) at the Center for Nanoscale Materials and the Advanced Photon Source (APS), both user facilities under the DOE Office of Science at Argonne. By scanning the sample with an X-ray beam just tens of nanometers wide while subjecting it to ultrafast light pulses, they obtained images showing the creation, erasure, and reconfiguration of the nanodomains. These structures changed across sizes ranging from 10 nanometers, about 10,000 times smaller than a human hair, to 10 micrometers, roughly the size of a cloud droplet. The final arrangement depended on the number of light pulses applied.
"By coupling an ultrafast laser to the Nanoprobe beamline, we can initiate and control changes to the networked nanodomains by means of light pulses without requiring much energy," said Martin Holt, an X-ray and electron microscopy scientist and group leader.
Initially, the material's nanodomains are arranged in a spiderweb-like pattern, but when disturbed by the light pulses, this structure breaks down and reforms into new configurations, functioning similarly to an adaptive network.
"We have discovered entirely new arrangements of these nanodomains," stated Stephan Hruszkewycz, an Argonne physicist and group leader. "The door is now wide open to many more discoveries. In the future, we will be able to test different regimes of light stimulation and observe even more unknown nanodomains and networks." With a recent upgrade to the APS, which now provides X-ray beams up to 500 times brighter, the capacity to visualize nanoscale changes over time will be significantly enhanced.
This discovery of time-dependent transformations in nanodomain networks marks a step toward developing adaptive networks for data storage and processing, potentially paving the way for more energy-efficient computing technologies.
Research Report:Optical Control of Adaptive Nanoscale Domain Networks
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Argonne National Laboratory
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