New property in warm superconductors discovered
Date: Monday, November 22, 2010 @ 22:36:31 GMT
Led by Simon Fraser University physicist Jeff Sonier, scientists at
TRIUMF have discovered something that they think may severely hinder the
creation of room-temperature (37 degrees Celsius) superconductors.
For 25 years, they’ve speculated that magnetism could be a problem.
The Proceedings of the National Academy of Sciences has
published the finding that there is a weak magnetism in a certain type
of lanthanum-based copper oxide material, which is the closest known
Sonier says: “The search for room-temperature superconductivity is big news. The cover story of the June 2010 issue of Scientific American predicted the discovery would be one of the ‘12 events that will change everything.’”
Superconductors, materials that have zero electrical resistance, could
potentially drive everyday devices in electronics, medicine and
transportation, but are super expensive because they only operate at
extremely low temperatures. If superconductors were operational at room
temperature they wouldn’t need to be driven by expensive cooling systems
using liquid helium.
When charge carriers are added to copper oxide materials, known as
cuprates, they are capable of superconductivity. Some cuprates function
at -140 degrees Celsius, a temperature markedly above -240 degrees
Celsius, which is the normal operational temperature of all other kinds
of superconducting materials.
Adding charge carriers (electric charge carrying particle) is known as
chemical doping. With increased chemical doping the operational
temperature of a cuprate superconductor rises to a certain point and
Until this latest research, scientists could only speculate on whether a
competing magnetic phase might exist during high chemical doping and
ultimately destroy their superconductivity.
Sonier and his colleagues used a subatomic particle, called a muon, to
microscopically probe the magnetic nature of a cuprate. This led them
to discover that a strange kind of magnetism appears to accompany the
destruction of superconductivity during high chemical doping.
The scientists are now trying to figure out the origin of the magnetism and whether it actually competes with superconductivity.
Sonier says, “Understanding what destroys superconductivity during high
chemical doping could provide a vital clue about the microscopic
mechanism responsible for high-temperature superconductivity. Knowledge
of this would be a monumental step toward making a room-temperature
A consortium of universities, including SFU, owns and operates
Vancouver-based TRIUMF. It is Canada’s national laboratory for particle
and nuclear physics.