New material could eliminate loss in electrical power transmission

The team's method for solving this energy problem is based upon the first realisation of an exotic type of magnetic semiconductor first theorised less than a decade ago – a magnetic topological insulator. The work is closely related to the quantum Hall effect, which is known to produce dissipationless electricity channels but requires large, cumbersome magnets to produce fields 100,000 larger than the earth's magnetic field for its operation. To overcome this, the researchers used the exotic type of semiconductor which exhibited a similar effect known as the quantum anomalous Hall effect. This stems from the semiconductor's own magnetisation rather than from an external one. At the heart of this effect is the interaction between magnetic ions and the topological insulator's current carrying particles, known as Dirac fermions, which are unique because they behave as if they have zero mass. The team says that the device it produced demonstrates that this new type of dissipationless transport can be harnessed in prototype transistors. Although the method currently requires cryogenic conditions, the team hope that improvements in material design will make operation possible at higher temperatures.