[freebeard]

A 17-year-old engineer's magnet-free motor prototype could make electric vehicles more sustainable

Clickbait title. "rare-earth-free magnets" buried at the end.

phys.org/news/2022-08: Unexpected quantum effects in natural double-layer graphene

The novel material graphene, a wafer-thin layer of carbon atoms, was first discovered by a British research team in 2004. Among other unusual properties, graphene is known for its extraordinarily high electrical conductivity. If two individual graphene layers are twisted at a very specific angle to each other, the system even becomes superconducting (i.e. conducts electricity without any resistance) and exhibits other exciting quantum effects such as magnetism. However, the production of such twisted graphene double-layers has so far required increased technical effort.

This novel study used the naturally occurring form of double-layer graphene, where no complex fabrication is required. In a first step, the sample is isolated from a piece of graphite in the laboratory using a simple adhesive tape. To observe quantum mechanical effects, the Göttingen team then applied a high electric field perpendicular to the sample: the electronic structure of the system changes and a strong accumulation of charge carriers with similar energy occurs.

At temperatures just above absolute zero of minus 273.15 degrees Celsius, the electrons in the graphene can interact with each other—and a variety of complex quantum phases emerge completely unexpectedly. For example, the interactions cause the spins of the electrons to align, making the material magnetic without any further external influence. By changing the electric field, researchers can continuously change the strength of the interactions of the charge carriers in the double-layer graphene. Under specific conditions, the electrons can be so restricted in their freedom of movement that they form their own electron lattice and can no longer contribute to transporting charge due to their mutual repulsive interaction. The system is then electrically insulating.

So we could postulate a swiched-reluctance motor constructed of graphene. Made with adhesive tape.

At -273.15° Celsius.