US researchers have developed ultrathin films that when sandwiched together form a superconductor, an advance that could lead to a new class of fast, power-saving electronics.

The films can be used at relatively high temperatures for superconductors, making them easier to handle and produce, they say.

"What we have done is we have put together two materials, neither of which is a superconductor, and we found their interface - where they touch - is superconducting," says physicist Dr Ivan Bozovic of the US Department of Energy's Brookhaven National Laboratory.

If cooled to the material's critical operating temperature, they have no resistance to the flow of electrical current, unlike ordinary electrical wires, which can eventually overheat.