Turning gold into spintronics

The scientists apparently investigated what happens in a device where a very thin layer of a superconductor – carrying electrical current but without generating any heat – is sandwiched between a layer of a magnetic material and a layer of gold.

Under certain conditions, it seems, the layer of gold becomes magnetic due to charge carriers flowing out of the superconductor into the metal.

The ability to generate and manipulate magnetic currents in this way could have potential for applications in new types of electronic devices, says the universities.

“Superconductors are materials that, if cooled sufficiently, lose their resistance, that is, they carry electricity without dissipating heat,” said Dr Machiel Flokstra, of the School of Physics and Astronomy at St Andrews, who led the team of collaborators.

“This is possible because the electrons that carry the electrical charge bind together into pairs that are able to move without losing energy. Each electron is itself like a tiny bar magnet, since these charged electrons spin about their own axes.”

“When they form into superconducting pairs these electronic `spins’ align oppositely, so that the magnetic fields cancel out. It transpires that in these new devices these pairs of electrons can be separated into two currents moving in opposite directions, one with magnetic fields (spins) pointing up and one with them pointing down.”

“The idea of generating `spin currents’ is the basis of the emerging field of spintronics. In conventional electronics only electrical charges can be manipulated, but it is hoped in the field of spintronics that electron spins can also be controlled, leading to novel advanced electronic devices.”

The experiments also involved the University of Bath, the University of Leeds, Royal Holloway and Bedford College (University of London), the ISIS Facility and the Paul Scherrer Institute in Switzerland. The large team of collaborators are led by Professor Steve Lee of the University of St Andrews (pictured).

The research is published on the Nature Physics website.