Topological insulators made magnetic

1 min read

A topological insulator (TI) film 25 atoms thick that adheres to an insulating magnetic film has been created by researchers from the University of California, Riverside, Massachusetts Institute of Technology and Arizona State University.

This is said to create a heterostructure, which makes TI surfaces magnetic at room temperatures and higher, to more than 400K.

"The materials have to be in intimate contact for TI to acquire magnetism," UC Riverside Professor Jing Shi said. "If the surface is rough, there won't be good contact. We're good at making this magnetic film atomically flat, so no extra atoms are sticking out."

The surfaces of TI need little power to conduct electricity. If TI surfaces are made magnetic, current only flows along the edges of the devices, requiring even less energy.

According to the research team, this quantum anomalous Hall effect (QAHE) makes devices very robust against defects or errors, so that a faulty application, for instance, doesn't crash an entire operating system.

Topological insulators are currently the only materials that can achieve the QAHE, but only after they are magnetised.

Scientists have been able to achieve magnetism in TI by doping. The doping allowed TI surfaces to demonstrate QAHE, but only at extremely low temperatures.

To find a different technique, the team created heterostructures of magnetic films and graphene materials by using laser molecular beam epitaxy. It then built 25 atomic TI layers on top of the magnetic sheets.

Using this technique, researchers claim a TI device could be tiny and its batteries long lasting.