Can current flow without electrons?

We all know that electricity is caused by electrons moving through metal. Each electron carries a discrete charge. The pictures are more complicated because the electrons repel each other.

Any movement from a single electron can interfere with the cloud of adjacent electrons. If the perturbation is mild, the electrons will eventually move in the clump, rather than as an isolated entity. Physicists call these group of electron quasi-particles. Finally, the current is still carried by discrete charges, but these discrete charges are not technically “free” electrons. For sixty years, this collective movement, called Fermi liquid, has been the standard theory of metals. Surprisingly, many new commanders, called “Strange Metal”, failed to adhere to this paradigm. In these materials, electricity is carried not by discrete fees, but by other fees! Using a measurement technique called Shot Noise, the researchers observed blurring the fundamental quantum of electrons into featureless fluid.

Influence
If a single electron does not carry electricity, what will happen? Fermi Liquid’s explanation of electrical transport is one of the basic successes of condensation physics, namely the study of solid matter. This new study challenges our current understanding and may lead to new electrical transmission theories. The impact may have reached a distance. For example, understanding the deviation from Fermi’s liquid behavior may reveal that the hidden function of high-temperature superconductors, in their normal, non-responsible state, behaves like strange metals.

Summary
The strange metal revolts against the Orthodox understanding of electric transmission through discrete charges. In these materials, the resistance varies linearly at low temperatures. In contrast, typical metal carriers have secondary behavior in resistance changes. To determine whether electricity is transported in discrete blocks, the researchers used a technique called Shot Noise. The shooting noise metric fluctuates randomly in the DC current. These random fluctuations occur because the current is the flow of discrete charges, and the arrival of each charge varies statistically. It’s like when a small amount of heavy rain hits the roof. Instead of hitting the roof at the same time, they assigned their arrival. In this case, the shooting noise is very high. In the other extreme case, if the rain is hard enough, there will be no dripping – the flow of rain is continuous and uncharacteristic. In this case, the shooting noise is zero. This seems to be something that happens in the weird metal!

Measuring shooting noise without external influence is not easy. In metals, vibrations from the atomic lattice can push electrons around and mask shooting noise. Researchers had to make such small nanoscale wires that electrons vibrate quickly through their ripples. These experiments provide strong evidence that in the strange metal YBRH2SI2 there are no quasi-particles and the current is not carried by discrete blocks. It’s like electrons lose their identity and fuse into quantum soup. The lack of quasi-particles is very powerful, and not all physicists are ready to accept it. These results will spark a series of high-profile investigations and contribute to the development of new strange metal theories.

funds
This work is funded by the Ministry of Energy Science Bureau of the Basic Energy Science Program, and is a research field in experimental condensed matter physics. Additional support is provided by the National Science Foundation, European Research Council, Austrian Science Foundation, Austrian Research Agency, EU Horizon 2020 Grant, U.S. Air Force Office of Scientific Research, Robert A. Welch Foundation Grant and Vannevar Bush Faculty Scholarship.