When you press a switch on any kind of electrical device, it triggers a marching band of charged particles to the beat of the circuit’s voltage.
But new discoveries of unusual materials known as strange metals suggest that electricity doesn’t always move in step and in fact sometimes makes physicists question what we know about the nature of particles. It turns out that bleeding can occur in this way.
The study was conducted on nanowires made with a precise balance of ytterbium, rhodium, and silicon (YbRh).2S2).
By conducting a series of quantum measurement experiments on these nanowires, researchers from the United States and Austria have produced evidence that may help resolve debates about the nature of electrical currents in metals that do not work in conventional ways. discovered.
discovered in the second half of the last century A type of copper-based compound known for its inability to withstand electrical current at relatively warm temperatures. strange metal Like other metals, heating it increases its resistance to electricity.
Only they do it in a rather strange way, the resistance increases by a set amount each time the temperature increases.
In normal metals, resistance changes with temperature, and once the material gets hot enough, resistance reaches a plateau.
This contrast in the laws of resistance suggests that electric currents in strange metals do not behave in exactly the same way. For some reason, the way charge-carrying particles in strange metals interact with the collisions of surrounding particles is different from the pinball slalom of electrons in your average strip of wire.
What we can imagine as a stream of negatively charged spheres rolling through a tube of copper atoms is a little more complicated. After all, electricity is a quantum matter, with the properties of a large number of particles that harmonize to behave like a single unit, known as quasiparticles.
It is an open question whether quasiparticles of the same type can explain the unusual resistive behavior of strange metals, and some theories and experiments suggest that such quasiparticles lose their integrity under the right circumstances. suggests that it is possible.
To find out whether there is a steady march of quasiparticles in the flow of electrons in strange metals, researchers exploited a phenomenon called . shot noise.
If time could be slowed down, the photons of light emitted by the most precise lasers would shoot out and splatter predictably into sizzling bacon fat. This “noise” is a feature of quantum probability and can provide a measure of the granularity of charge flowing in a conductor.
“The idea is that if you’re driving a current, that current is made up of many individual charge carriers.” To tell Lead author Doug Natelson is a physicist at Rice University in the US.
“They arrive at an average speed, but sometimes they just happen to be closer together in time, and sometimes farther away.”
The research team discovered shot noise measurements from ultrathin samples of YbRh.2S2 It is highly suppressed in a way that cannot be explained by typical interactions between electrons and their environment, suggesting that quasiparticles are probably not involved.
Instead, the electric charge is more like a liquid than the electric current of traditional metals, and the discovery supports this. proposed model It was written more than 20 years ago by contributor Qimiao Si, a condensed matter physicist at Rice University.
Si’s theory of materials as the temperature approaches 0 degrees Celsius explains how electrons within selected locations no longer share the properties that allow quasiparticle formation.
Although classical quasiparticle behavior can be tentatively ruled out, further research into what form this “liquid” current might take, and whether it might even be found in other strange metal recipes, remains to be seen. The team isn’t entirely sure.
“Perhaps this is evidence that quasiparticles are not well-defined or simply do not exist, and charges move in a more complex way. How charges move collectively I need to find the right vocabulary to explain it.” To tell Natelson.
This study science.