Friday, February 9, 2007

Ongoing Research

Ongoing Research
A small sample of the high-temperature superconductor BSCCO-2223. The two lines in the background are 1 mm apart.
One of the top unsolved problems in modern physics is the question of how superconductivity arises in these materials, that is, what mechanism causes the electrons in these crystals to form pairs.
Despite much intensive research and many promising leads, an answer to this question has so far eluded scientists. One reason for this is that the materials in question are generally very complex, multi-layered crystals (for example, BSCCO), making theoretical modeling difficult. But with the rapid rate of new, important discoveries in the field, many researchers are optimistic that a complete understanding of the process is possible within the next decade or so.

High-temperature superconductivity

High-temperature superconductivity
From Wikipedia, the free encyclopedia
(Redirected from High-temperature superconductor)

Unsolved problems in physics: Why do certain materials exhibit superconductivity at temperatures much higher than 50 K? Is room-temperature superconductivity possible?
High-temperature superconductors are generally considered to be those that demonstrate superconductivity at or above the temperature of liquid nitrogen, or −196 °C (77 K), since this is the most easily attainable cryogenic temperature. Conventional superconductors, by contrast, require temperatures no higher than a few degrees above absolute zero (−273.15 °C or −459.67 °F).
A "high-temperature" superconductor levitates a magnet (with boiling liquid nitrogen underneath) demonstrating the Meissner effect, one of the hallmark properties of superconductivity.
The term high-temperature superconductor was first used to designate the new family of cuprate-perovskite ceramic materials discovered by Johannes Georg Bednorz and Karl Alexander Müller in 1986,[1] for which they won the Nobel Prize in Physics the following year. Their discovery of the first high-temperature superconductor LaBaCuO, with a transition temperature of 35 K, generated much excitement because it was previously widely assumed to be impossible for superconductivity to occur at such "high" temperatures.
Recently, other unconventional superconductors have been discovered. Some of them also have unusually high values of the critical temperature Tc, and hence they are sometimes also called high-temperature superconductors, although the record is still held by a cuprate-perovskite material (Tc=138 K, that is −135 °C), although slightly higher transition temperatures have been achieved under pressure.[2] Nevertheless, it is believed by some researchers that if a room temperature superconductor is ever discovered it will be in a different family of materials.[

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