After years of searching, physicists watch electrons flow into fluid-like whirlpools

(ORDO NEWS) — For the first time, physicists have witnessed an incredibly exciting phenomenon: electrons form whirlpools just like a liquid.

Scientists have long predicted this behavior, but have never observed it before. And this could be the key to developing more efficient and faster next-generation electronics.

“Electronic vortices are expected in theory, but there is no direct evidence, and to see is to believe,” says one of the researchers. The physicist Leonid Levitov from the Massachusetts Institute of Technology is behind the new study.

“Now we’ve seen it, and it’s a clear sign that we’re in this new mode where the electrons behave like a fluid rather than like individual particles.”

While the electrons are flowing in a vortex it might not seem that innovative, it’s a big deal because flow like a fluid results in more energy being delivered to the end point rather than being lost along the way when the electrons are pushed around by things like impurities in the material or vibration. in atoms.

“We know that when electrons go into a liquid state, [energy] dissipation drops, and this is of interest for the development of low-power electronics,” Levitov says. “This new observation is another step in that direction.”

This work was a collaborative experiment between the Massachusetts Institute of Technology, the Weizmann Institute of Science in Israel, and the University of Colorado Denver.

>Of course, we already know that electrons can bounce off each other and flow without resistance in superconductors, but this is the result of the formation of something known as “Cooper pairs”, and this is not a real example of the collective movement of electrons like a liquid.

Let’s take water for example. Water molecules are separate particles, but they move as a whole in accordance with the principles of hydrodynamics, carrying each other over the surface, forming streams and whirlpools on their way.

Electric current, in fact, should be capable of the same thing, but any collective behavior of electrons is usually suppressed by impurities and vibrations in normal metals and even semiconductors. These “distractions” knock the electrons out of place as they move and prevent them from behaving like a liquid.

It has long been predicted that in special materials at temperatures close to zero, these interferences should disappear, allowing electrons to move like a liquid … but the problem was that no one could prove that this was really the case. , still.

There are two main characteristics of a fluid: linear flow, where all the individual particles move in parallel as a whole; and the formation of eddies and whirlpools.

The first was observed by Levitov and colleagues at the University of Manchester back in 2017 using graphene.

On atom-thin sheets of carbon, Levitov and his team showed that electric current could flow through a pinch point like a liquid, not like grains of sand.

But no one saw the second feature. “The most striking and ubiquitous feature of the flow of ordinary fluids – vortex formation and turbulence – has not yet been observed in e-liquids, despite numerous theoretical predictions,” the researchers write.

To figure this out, the team took pure single crystals of an ultrapure material known as tungsten ditelluride (WTe 2 ) and cut flakes one atom thick.

They then engraved the design into the central channel with round chambers on either side, creating a “maze” through which the electrical current passed.

They engraved the same pattern on flakes of gold, which does not have the same ultra-pure properties as tungsten ditelluride, and therefore served as a control.

After cooling the material to approximately -269 degrees Celsius (4.5 Kelvin or -451.57 Fahrenheit). they ran an electric current through it and measured the flow at specific points throughout the material to map out the movement of the electrons.

In the gold flakes, the electrons flowed through the maze without changing direction, even as the current passed through each side chamber, before returning to the main current.

In contrast, inside the tungsten ditelluride, the electrons flowed through the channel and then swirled into each side chamber, creating whirlpools before flowing back. into the main channel – as you would expect from a liquid.

“We observed a change in flow direction in chambers where the direction of flow was reversed from that in the central lane. Levitov says.

“It’s very amazing, and it’s the same physics. sics as in ordinary liquids, but occurs with electrons at the nanoscale. This is a clear sign that the electrons are in a liquid mode.”

After years of searching physicists watch electrons flow into fluid like whirlpools 2
The column on the left shows how electrons flow through tungsten ditelluride compared to the hydrodynamic simulation in the left column

Of course, this experiment was conducted at ultra-low temperatures with a special material – this is not something that will be happening in your home gadgets anytime soon. There were also restrictions on the size of the cameras and the middle channel.

But this is “the first direct visualization of rotating vortices in an electric current,” as the press release explains.

Not only is this confirmation that electrons can behave like a liquid, but the advance could help engineers better understand how to use this potential in their devices.


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