Chris Muirhead

Superconductors

making things clearer for mobiles, moons and medicine

What is a Superconductor?

Figure 1 - Microphotograph of a superconducting device which measures about a thousandth of a millimetre in size.

Superconductors are amazing materials whose

resistance drops to zero when cooled. In other words,

very efficient conductors. Commonly used superconducting

materials are complex metal oxides (of, for example,

yittrium, barium copper oxide) and they typically

become superconducting when cooled below around

-180 degrees Centigrade. Cooling can be achieved

using liquid nitrogen which is cheaply available.

In addition to zero resistance, superconductors

have other useful properties. They are impervious

to certain strengths of magnetic field enabling

magnetic levitation; superconducting devices called

SQUIDS are sensitive magnetic field detectors. SQUID

devices are able to detect magnetic fields 10,000

million times smaller than the Earth's magnetic

field. Superconducting microelectronic devices can

be made of layers of thin films of superconducting

material only a few hundred nanometres thick (Figure

1).

 

What are they used for?

Superconducting electronic devices outperform

and are smaller than their traditional counterparts.

As parts of communication systems they have application

in space exploration, mobile communications and

aerospace. For example, a University of Birmingham

superconducting filter is installed in the Jodrell

Bank radio telescope to filter out atmospheric noise

(signals from satellites, television receivers etc).

This can dramatically improve the clarity of the

images of pulsars, quasars and galaxies received

and enables more distant targets with weaker signals

to be detected. A superconducting receiver on trial

in mobile phone base stations has the potential

to increase the range and reduce the number of mobile

phone masts. Magnetic levitation offers exciting

possibilities for transport, with a superconducting

train which "floats" above the rails already

in operation in Japan. Superconducting magnets have

for a long time been used in body scanners, but

SQUIDS are now used in detection of brain and foetal

activity. SQUIDS are also being investigated for

application in quantum computers, an emerging breed

of super-fast computers.

A member of the superconductivity research team demonstrating coolants to school children.

 

"The dream is code breaking,

super-secure, quantum computers."

Dr Chris Muirhead, School of Physics and Astronomy

 

Superconductivity at the University of Birmingham

The Birmingham Portfolio Partnership is a £6M

research grant from The Engineering and Physical

Sciences Research Council (EPSRC). The award, entitled

"Superconducting Thin Films - Their Science

and Applications", is between the School of

Engineering and the School of Physics and Astronomy

at The University of Birmingham. The research is

at the forefront in Europe and in Engineering centres

on the invention, production and application of

new superconducting materials and devices. The work

in Physics develops and applies techniques for investigating

and exploiting the properties of these new materials.

 

Would you like to know more?

If you would like to know more about the subject

or research, particularly if you would like a school

visit, please contact the Outreach Manager for The

Birmingham Portfolio Partnership at superconductivity@bham.ac.uk

or on 0121 414 7405.

- October 2006

About the Author

Chris is a lecturer at Birminham University developing superconducting devices.