Flipping a switch on any type of electrical device releases an array of charged particles that move to the rhythm of the circuit’s voltage.
But a new discovery in strange materials known as exotic metals has found that electricity doesn’t always move in steps, and can in fact sometimes bleed in a way that has physicists questioning what we know about the nature of particles.
The research was conducted on nanowires made from a precise balance of ytterbium, rhodium, and silicon (YbRh).2bad2).
By performing a series of quantitative experiments on these nanowires, researchers from the United States and Austria have uncovered evidence that could help settle the debate about the nature of electric currents in metals that do not behave in a conventional way.
It was discovered in the late last century In a class of copper-based compounds known to have no resistance to currents at relatively warm temperatures, Exotic minerals It becomes more resistant to electricity when heated, just like any other metal.
However, it does this in a somewhat strange way, where the resistance increases by a certain amount for each degree of temperature rise.
In ordinary metals, resistance varies depending on temperature, and stabilizes once the material becomes hot enough.
This variation in resistance rules indicates that currents in exotic metals do not operate in exactly the same way. For some reason, the way charge-carrying particles in exotic metals interact with the jostling particles around them is different from the zig-zagging of electrons in a pinball in the average wire strand.
What we might envision as a stream of negatively charged balls flowing through a tube of copper atoms is a bit more complex. Electricity is ultimately a quantum matter, where the properties of a number of particles harmonize to behave as single units known as quasiparticles.
Whether the same types of quasiparticles explain the unusual resistive behaviors of exotic metals is an open question, as some theories and experiments suggest that such particles may lose their integrity under the right conditions.
To clarify whether there is a steady march of quasiparticles in the flow of electrons in exotic metals, the researchers used a phenomenon called… Fire noise.
If you could slow down time to a crawl, the photons of light emitted by even the most precise laser would explode and scatter with all the predictability of sizzling bacon grease. This “noise” is a feature of quantum probability, and can provide a measure of the details of charges as they flow through the conductor.
“The idea is that if I’m driving a current, it’s made up of a bunch of separate charge carriers,” he said. He says Senior author Doug Natelson, a physicist at Rice University in the US.
“These arrive at an average rate, but sometimes they are closer together in time, and sometimes they are farther apart.”
The team found measurements of shot noise in their extremely thin sample of YbRh2bad2 They were greatly suppressed in ways that typical interactions between electrons and their environment could not explain, suggesting that quasiparticles probably did not exist.
Instead, the charge was more liquid-like than the currents found in conventional metals, a finding that supports it Proposed model More than 20 years ago by contributing author Kimiao Si, a condensed matter physicist from Rice University.
Si theory of materials at near-zero temperatures describes the way in which electrons in specific locations no longer share properties that allow them to form quasiparticles.
While conventional quasiparticle behavior can be ruled out in principle, the team isn’t entirely sure what form this “liquid” stream takes, or even whether it can be found in other exotic metallic recipes.
“Maybe this is evidence that quasiparticles are not well-defined things or don’t exist, and charge moves in more complex ways. We have to find the right vocabulary to talk about how charge moves collectively.” He says Natelson.
This research was published in Sciences.
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