Abstract:
Physicists at Auburn University in the United States have discovered that brief laser pulses can induce an ordered electrical polarization state inside a specific crystal, even if the material is at a higher temperature and the tiny polarized areas inside are usually still chaotic. This discovery provides a new method for studying extremely fast electrical changes within materials, and may help explore ultra-high-speed information processing and storage technologies in the future.
This research focuses on modified strontium titanate single crystals. The material has a special property: electrons can move within it, and there are a large number of tiny polarized regions inside. These areas have asymmetry in the distribution of positive and negative charges, which can be understood as micro-electropolarization units with different directions inside. The researchers call this a "polar nanoregion."
Under normal circumstances, temperature changes affect the alignment of these polarized regions. As the crystal cools, the originally oriented regions gradually assume more regular orientations; at higher temperatures, they tend to be in a more disordered state. However, scientists have long debated whether this ordered state is formed by the coordinated displacement of atoms, or whether there are polarized regions inside the crystal that are gradually aligned during the cooling process.
Distinguishing the two explanations is not easy because the size of the polarized regions is extremely small and the resulting signals are very weak. The Auburn University research team was led by physicist Wencan Jin, and graduate student Mohammad Qandil participated in the core experiment. Researchers from the Japan Institute of Advanced Industrial Science and Technology are responsible for growing crystal samples required for experiments.
The research team established a highly sensitive laser measurement system and spent nearly a year continuously improving the equipment to capture extremely weak optical signals inside the crystal. By observing the crystal's response to incident light, the researchers tracked the orientation changes of the polarized regions as they repeatedly heated and cooled.
The measurement results show that at higher temperatures, the directions of the polarization regions are more dispersed; as the temperature decreases, they gradually show more obvious preferred orientations. This provides strong evidence for an important explanation: the polarized regions may have existed before the arrangement became ordered, and the cooling process mainly changed their arrangement.
The researchers didn't stop at observing temperature changes, though. They further tried to use lasers to directly control these polarization regions, so that the originally disordered electrical polarization state could be transformed into an ordered state in a very short time.
This key breakthrough will occur in 2025. The researchers observed that laser irradiation can prompt the polarization regions with different directions inside the crystal to quickly align. The ordered state induced by light lasted only about 1 picosecond, or a trillionth of a second, and then quickly disappeared.
Although it was extremely short-lived, the researchers were able to detect the change through optical measurements. This means that the laser can not only affect the electrical state inside the material, but also create an ordered structure that can be measured in a very short time.
The significance of this phenomenon is that it provides scientists with a new tool to study the ultrafast electrical behavior within materials. Traditional methods of material control usually rely on temperature, electric field or other relatively slow external conditions, while laser pulses can change the state of materials in a very short time, allowing researchers to observe transient processes that are difficult to capture with conventional experimental methods.
Researchers believe that this discovery may be related to ultra-high-speed information processing and storage technology in the future. If scientists can further understand how to use light pulses to establish, read and control ordered states in materials, there will be opportunities to explore new electronic devices that use light as a means of control. Because light pulses can act on materials in extremely short periods of time, this research direction is also expected to help people understand and develop faster physical processes.
However, the current experiments do not mean that the research team has created an ultra-fast memory or processor that can actually work. The laser-induced ordered state can only last about 1 picosecond. How to extend its duration, achieve stable and repeatable control, and integrate this phenomenon into actual devices are still problems that need to be solved.
This research result was published in the journal "Physical Review Letters" on October 14, 2026. The paper is titled "Optical Polarization Control of Quantum Ferroelectric Metals Across Order-Disorder Phase Transition". The research provides new evidence for understanding the formation and arrangement of polarized regions within crystals, and also demonstrates the possibility of using light pulses to manipulate the electrical state of materials.
From a broader materials science perspective, the value of this work lies not only in the discovery of a new laser control phenomenon, but also in the ability of researchers to observe and control microscopic structures inside materials that are otherwise difficult to detect directly with the help of extremely brief optical signals. In the future, as measurement technology and material design continue to advance, similar methods may help scientists develop new electronic devices and further explore the application potential of the interaction of light and matter in information technology.
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