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Univ. of Toronto Physicists Develop Technique for Bonding Semiconductors to Superconductors

Published on 2012-09-17. Author : SpecialChem

An international team led by University of Toronto physicists has developed a simple new technique to induce high-temperature superconductivity in a semiconductor for the first time - using Scotch Tape.

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?" said team leader and U of T physicist Ken Burch.

High-temperature superconductors are materials that conduct electricity without heating up or losing energy at liquid nitrogen temperatures. Used to transmit electricity with low loss, these superconductors are also the building blocks of the next generation of devices such as 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 semi-conductors, so their 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 semi-conductor - has been difficult because the fundamental quantum mechanics require the materials to be in nearly perfect contact.

That's where the tape comes in - specifically, Scotch poster tape: a thin, two-sided version of Scotch Tape.

"Typically, junctions between semi-conductors 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."

The team used Scotch poster tape and glass slides to place high-temperature superconductors in proximity with a special type of semi-conductor known as a topological insulator. Topological insulators have captured world-wide attention from scientists because they behave like semi-conductors in bulk, but are very metallic at the surface.

The result - induced superconductivity in these novel semi-conductors - was a physics first.

In addition to Burch, the U of T team included Alex Hayat, Parisa Zareapour, Shu Yang F. Zhao, Michael Kreshchuk, Achint Jain. All are members of the Department of Physics and Institute for Optical Sciences and Hayat holds an additional appointment with U of T's Centre for Quantum Information and Quantum Control.

Other scientists collaborating on the project are: Sang-Wook Cheong, Daniel C. Kwok and Nara Lee of Rutgers University, G.D. Gu, Ahijun Xu and Zhijun Xu of Brookhaven National Laboratory and Robert Cava of Princeton.

The work 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.

About University of Toronto

The University of Toronto has assembled one of the strongest research and teaching faculties in North America, presenting top students at all levels with an intellectual environment unmatched in breadth and depth on any other Canadian campus. U of T faculty co-author more research articles than their colleagues at any university in the US or Canada other than Harvard. As a measure of impact, U of T consistently ranks alongside the top five U.S. universities whose discoveries are most often cited by other researchers around the world. The U of T faculty are also widely recognized for their teaching strengths and commitment to graduate supervision.

Source: University of Toronto


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