Zurich - Researchers at the Swiss Federal Institute of Technology in Zurich (ETH) have for the first time made visible the formation of vortices during the flow of electrons in a material. They used the extremely thin material graphene. The experiment was conducted at room temperature.
ETH researchers detect vortices in electron flow
Using a magnetic field sensor (red arrow) inside a diamond needle, researchers at ETH imaged electron vortices in a graphene layer (blue). (Illustration: Chaoxin Ding)


Researchers at the Swiss Federal Institute of Technology in Zurich (ETH) have for the first time directly detected the formation of vortices during the flow of electrons. According to a statement, Christian Degen's research group was able to directly detect electron vortices in graphene. The observations could build the foundations for the development of more efficient electronics with low power consumption. Energy loss decreases when electrons are in a liquid state.

To prove that electrons in a material behave like liquids, the researchers used the extremely thin material graphene, a carbon layer only one atom “wide”. Typically, the electron flow can be detected at very low temperatures. The ETH researchers have now succeeded in doing so at room temperature.

To make the vortices visible, the scientists measured the tiny magnetic fields generated by the electrons moving in the graphene. To do this, they used a quantum magnetic field sensor consisting of a so-called nitrogen-vacancy colour centre in the tip of a diamond needle. “Because of the tiny dimensions of the diamond needle and the small distance from the graphene layer – only around 70 nanometres – we were able to make the electron currents visible with a resolution of less than a hundred nanometres,” Marius Palm, a former PhD student in Degen’s group, is quoted as saying. This resolution is sufficient for seeing the vortices.

“At this moment, the detection of electron vortices is basic research, and there are still lots of open questions,” Palm continues. The new detection method used by the ETH researchers permits taking a closer look at many other electron transport effects,  according to the statement. The study was published in the journal “Science”. ce/gba 

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