An international team led by University of Toronto (U of T) physicists
has developed a simple new technique using Scotch poster tape that has enabled
them to induce high-temperature superconductivity in a semiconductor for the
first time. The method paves the way for novel 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 U of T 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—wherein 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 makeup 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. 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 semi-conductors: a physics first.
Source: University of Toronto
