Researchers at Northeastern University have found a way to control how a quantum material behaves — switching it between conducting electricity and blocking it — using a method called thermal quenching, which involves carefully heating and cooling the material. This breakthrough could lead to electronics that are up to 1000 times faster than today’s silicon-based devices.
The material they worked with is called 1T-TaS₂, a transition metal dichalcogenide crystal. Normally, it only shows a special metallic state at extremely cold temperatures, which makes it hard to use in everyday devices. But the team discovered how to make this state stable at much warmer temperatures, close to room level, and keep it that way for months. That’s a big step forward, since earlier attempts only lasted for tiny fractions of a second.
“Processors work in gigahertz right now,” said Alberto de la Torre, assistant professor of physics and lead author of the study. “The speed of change that this would enable would allow you to go to terahertz.”
To make this happen, the researchers used light to trigger changes in the material. They found that by combining different charge density wave (CDW) patterns, which are ways electrons organize themselves, they could stabilize a hidden metallic CDW state. This state had previously only appeared at cryogenic temperatures and was not well understood. Now, they’ve shown it can exist up to 210 K (−63°C), which is much more practical.
They used advanced tools like X-ray mapping and scanning tunnelling spectroscopy to study the material. These revealed that the metallic and insulating regions inside the material have different mirror symmetry patterns and even cause the unit cell, the basic building block of the crystal, to triple in size in one direction. Even though there are metallic areas and a measurable density of states, the material still acts as an insulator overall because of how the CDW layers stack up.
“Everyone who has ever used a computer encounters a point where they wish something would load faster,” said Gregory Fiete, professor of physics at Northeastern. “There’s nothing faster than light, and we’re using light to control material properties at essentially the fastest possible speed that’s allowed by physics.”
This kind of control is similar to how transistors work, but instead of needing separate materials and complex interfaces, the researchers can now use just one material and control it with light. That could make future devices simpler and more efficient.
“We eliminate one of the engineering challenges by putting it all into one material,” Fiete said. “And we replace the interface with light within a wider range of temperatures.”
The discovery also opens up new possibilities for designing electronics beyond what silicon can offer. As chips get more crowded and engineers start stacking them in 3D, there’s a need for new materials that can do more in less space.
“One of the grand challenges is, how do you control material properties at will?” said Fiete. “What we’re shooting for is the highest level of control over material properties. We want it to do something very fast, with a very certain outcome, because that’s the sort of thing that can be then exploited in a device.”
“We’re at a point where in order to get amazing enhancements in information storage or the speed of operation, we need a new paradigm,” he added. “Quantum computing is one route for handling this and another is to innovate in materials. That’s what this work is really about.”
Source: Northeastern University, Nature | Image via Depositphotos
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