U. TORONTO (CAN) — A simple technique using Scotch poster tape has induced high-temperature superconductivity in a semiconductor for the first time.
The method paves the way for new devices that could be used in quantum computing and to improve energy efficiency.
“Who would have thought simply sticking things together can generate entirely new effects?” says team leader and University of Toronto physicist Ken Burch.
High-temperature superconductors are materials that conduct electricity without heating up and losing energy at liquid nitrogen temperatures. They are currently in use for transmitting electricity with low loss and as the building blocks of the next generation of devices (quantum computers).
However, only certain compounds of iron, copper, and oxygen—or cuprates—reveal high-temperature superconducting properties. Cuprates were believed to be impossible to incorporate with semiconductors, and so their real-world use has been severely limited as has the exploration of new effects they may generate.
For example, observing the phenomenon of the proximity effect—where the superconductivity in one material generates superconductivity in an otherwise normal semiconductor—has been difficult because the fundamental quantum mechanics require the materials to be in nearly perfect contact.
That’s where the poster tape comes in.
“Typically, junctions between semiconductors and superconductors were made by complex material growth procedures and fabricating devices with features smaller than a human hair,” explains Burch. “However the cuprates have a completely different structure and complex chemical make-up that simply can’t be incorporated with a normal semiconductor.”
So instead, the team used Scotch poster tape and glass slides to place high-temperature superconductors in proximity with a special type of semiconductor known as a topological insulator. They explain the approach in a paper published in the journal Nature Communications.
Topological insulators have captured world-wide attention from scientists because they behave like semiconductors in the bulk, but are very metallic at the surface. The result was induced superconductivity in these novel semiconductors: a physics first.
Other scientists from the University of Toronto, Rutgers University, Brookhaven National Laboratory, and Princeton University collaborated on the project, which was supported by the Natural Sciences and Engineering Research Council of Canada, the Canadian Foundation for Innovation, the Ontario Ministry for Innovation, and the National Science Foundation.
Source: University of Toronto