"In the late 1980s, Pacific Northwest National Laboratory researchers conducted research into superconductors. The ceramic superconductors are made from a material that has only very low alternating-current resistance and thus dissipates less power. Magnetic forces between the magnet and ceramic superconductor provide a magnetic cushion that keeps the magnet suspended above the superconductor. Liquid nitrogen cools the superconductor to about 77 Kelvin, producing the magnetic cushion." (Source: Pacific Northwest National Laboratory)
Scientists observe how superconductivity truly works; advance efforts to find high temperature superconducting materials
One of the greatest mysteries of science is superconductivity. Superconductivity, a term that entered popular lexicon with the advent of magnetic levitation, is an incredible phenomenon. At extremely low temperatures certain materials known as superconductors lose almost all resistance to electricity and experience exclusion of the inner magnetic field -- also known the Meissner Effect.
Traditional electric-conducting materials such as gold or copper have impurities that prevent them from superconducting. These materials have a discrete resistance, even at absolute zero -- a theoretical point of zero Kelvins, or -273.14 degrees Celsius. Superconductors experience resistance down to a critical temperature, known as Tc. Once the temperature drops to this point, the materials begin to superconducting and reach a point of zero resistance.
Superconductors hold tremendous promise as a computer system
utilizing a superconducting circuitry loop could exist indefinitely
without a power source, and would be far more efficient as it would not output waste
heat.
Extremely promising research occurred during the last three decades into discovering "high temperature" superconductors. The first superconductors discovered required tremendous cooling to take them to almost absolute zero before superconduction.
No room-temperature superconductor has been observed but the field experienced a revolution in 1986 with the discovery of cuprate-perovskite material superconductors, which could superconduct at temperatures in excess of 90 degrees Kelvin. The highest temperature superconductor currently known is a ceramic material consisting of thallium, mercury, copper, barium, calcium, strontium and oxygen, which has a Tc= 138 K (-135.14 °C).
These discoveries created materials that can achieve superconduction with mere liquid nitrogen cooling -- a relatively economical prospect.
One difficulty in discovering higher temperature materials is that scientists did not understand what caused superconducting phenomena on an atomic level. A great deal of research in quantum physics has gone into this topic, but much confusion remained. Scientists knew that superconducting materials form pairs of electrons known as Cooper pairs.
Researchers at the University of Tennessee and Oak Ridge National Laboratory led by Professor of physics Pengcheng Dai claim to know the cause of superconductivity. The team's work, published at Boston College (PDF), details how special subatomic vibrations in crystal latices dubbed phonons bind the electrons together magnetically, and thus allow superconduction.
Dai claims in University of Tennessee press release, "These findings add to the understanding that magnetism plays a role in creating these important pairs. This will not end the debate, but it's another step."
Still, this research, if it should withstand the eye of scrutiny of the scientific community, will be one of the most important breakthroughs in the understand of how superconduction works. This in turn will allow scientists to easily and procedurally derive new high-temperature superconductors, pushing the temperature higher and higher, possibly one day into the room temperature range.
"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson
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